StringUtils (Steve Wedig's Libraries for Java 7+ 2.0.2 API)

java.lang.Object
- com.stevewedig.blog.apache.commons.lang3.StringUtils

```
public abstract class StringUtils
extends Object
```
Operations on String that are null safe.
- IsEmpty/IsBlank - checks if a String contains text
- Trim/Strip - removes leading and trailing whitespace
- Equals - compares two strings null-safe
- startsWith - check if a String starts with a prefix null-safe
- endsWith - check if a String ends with a suffix null-safe
- IndexOf/LastIndexOf/Contains - null-safe index-of checks
- IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
- ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
- Substring/Left/Right/Mid - null-safe substring extractions
- SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
- Split/Join - splits a String into an array of substrings and vice versa
- Remove/Delete - removes part of a String
- Replace/Overlay - Searches a String and replaces one String with another
- Chomp/Chop - removes the last part of a String
- AppendIfMissing - appends a suffix to the end of the String if not present
- PrependIfMissing - prepends a prefix to the start of the String if not present
- LeftPad/RightPad/Center/Repeat - pads a String
- UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
- CountMatches - counts the number of occurrences of one String in another
- IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
- DefaultString - protects against a null input String
- Reverse/ReverseDelimited - reverses a String
- Abbreviate - abbreviates a string using ellipsis
- Difference - compares Strings and reports on their differences
- LevenshteinDistance - the number of changes needed to change one String into another
The StringUtils class defines certain words related to String handling.
- null - null
- empty - a zero-length string ("")
- space - the space character (' ', char 32)
- whitespace - the characters defined by Character.isWhitespace(char)
- trim - the characters <= 32 as in String.trim()
StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils.

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#
Since:

1.0

Version:

$Id$

See Also:
String

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`CR` A String for carriage return CR ("\r").
`static String`	`EMPTY` The empty String `""`.
`static int`	`INDEX_NOT_FOUND` Represents a failed index search.
`static String`	`LF` A String for linefeed LF ("\n").
`static String`	`SPACE` A String for a space character.

Constructor Summary

Constructors
Constructor and Description

StringUtils()
StringUtils instances should NOT be constructed in standard programming.

Constructors
Constructor and Description
`StringUtils()` `StringUtils` instances should NOT be constructed in standard programming.

Method Summary

Methods
Modifier and Type	Method and Description
`static String`	`abbreviate(String str, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviate(String str, int offset, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviateMiddle(String str, String middle, int length)` Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.
`static String`	`appendIfMissing(String str, CharSequence suffix, CharSequence... suffixes)` Appends the suffix to the end of the string if the string does not already end with any the suffixes.
`static String`	`appendIfMissingIgnoreCase(String str, CharSequence suffix, CharSequence... suffixes)` Appends the suffix to the end of the string if the string does not already end, case insensitive, with any of the suffixes.
`static String`	`center(String str, int size)` Centers a String in a larger String of size `size` using the space character (' ').
`static String`	`center(String str, int size, char padChar)` Centers a String in a larger String of size `size`.
`static String`	`center(String str, int size, String padStr)` Centers a String in a larger String of size `size`.
`static String`	`chomp(String str)` Removes one newline from end of a String if it's there, otherwise leave it alone.
`static String`	`chop(String str)` Remove the last character from a String.
`static boolean`	`contains(CharSequence seq, CharSequence searchSeq)` Checks if CharSequence contains a search CharSequence, handling `null`.
`static boolean`	`contains(CharSequence seq, int searchChar)` Checks if CharSequence contains a search character, handling `null`.
`static boolean`	`containsAny(CharSequence cs, char... searchChars)` Checks if the CharSequence contains any character in the given set of characters.
`static boolean`	`containsAny(CharSequence cs, CharSequence searchChars)` Checks if the CharSequence contains any character in the given set of characters.
`static boolean`	`containsIgnoreCase(CharSequence str, CharSequence searchStr)` Checks if CharSequence contains a search CharSequence irrespective of case, handling `null`.
`static boolean`	`containsNone(CharSequence cs, char... searchChars)` Checks that the CharSequence does not contain certain characters.
`static boolean`	`containsNone(CharSequence cs, String invalidChars)` Checks that the CharSequence does not contain certain characters.
`static boolean`	`containsOnly(CharSequence cs, char... valid)` Checks if the CharSequence contains only certain characters.
`static boolean`	`containsOnly(CharSequence cs, String validChars)` Checks if the CharSequence contains only certain characters.
`static boolean`	`containsWhitespace(CharSequence seq)` Check whether the given CharSequence contains any whitespace characters.
`static int`	`countMatches(CharSequence str, char ch)` Counts how many times the char appears in the given string.
`static int`	`countMatches(CharSequence str, CharSequence sub)` Counts how many times the substring appears in the larger string.
`static <T extends CharSequence> T`	`defaultIfBlank(T str, T defaultStr)` Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or `null`, the value of `defaultStr`.
`static <T extends CharSequence> T`	`defaultIfEmpty(T str, T defaultStr)` Returns either the passed in CharSequence, or if the CharSequence is empty or `null`, the value of `defaultStr`.
`static String`	`defaultString(String str)` Returns either the passed in String, or if the String is `null`, an empty String ("").
`static String`	`defaultString(String str, String defaultStr)` Returns either the passed in String, or if the String is `null`, the value of `defaultStr`.
`static String`	`deleteWhitespace(String str)` Deletes all whitespaces from a String as defined by `Character.isWhitespace(char)`.
`static String`	`difference(String str1, String str2)` Compares two Strings, and returns the portion where they differ.
`static boolean`	`endsWith(CharSequence str, CharSequence suffix)` Check if a CharSequence ends with a specified suffix.
`static boolean`	`endsWithAny(CharSequence string, CharSequence... searchStrings)` Check if a CharSequence ends with any of an array of specified strings.
`static boolean`	`endsWithIgnoreCase(CharSequence str, CharSequence suffix)` Case insensitive check if a CharSequence ends with a specified suffix.
`static boolean`	`equals(CharSequence cs1, CharSequence cs2)` Compares two CharSequences, returning `true` if they represent equal sequences of characters.
`static boolean`	`equalsIgnoreCase(CharSequence str1, CharSequence str2)` Compares two CharSequences, returning `true` if they represent equal sequences of characters, ignoring case.
`static String`	`getCommonPrefix(String... strs)` Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.
`static double`	`getJaroWinklerDistance(CharSequence first, CharSequence second)` Find the Jaro Winkler Distance which indicates the similarity score between two Strings.
`static int`	`getLevenshteinDistance(CharSequence s, CharSequence t)` Find the Levenshtein distance between two Strings.
`static int`	`getLevenshteinDistance(CharSequence s, CharSequence t, int threshold)` Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.
`static int`	`indexOf(CharSequence seq, CharSequence searchSeq)` Finds the first index within a CharSequence, handling `null`.
`static int`	`indexOf(CharSequence seq, CharSequence searchSeq, int startPos)` Finds the first index within a CharSequence, handling `null`.
`static int`	`indexOf(CharSequence seq, int searchChar)` Finds the first index within a CharSequence, handling `null`.
`static int`	`indexOf(CharSequence seq, int searchChar, int startPos)` Finds the first index within a CharSequence from a start position, handling `null`.
`static int`	`indexOfAny(CharSequence cs, char... searchChars)` Search a CharSequence to find the first index of any character in the given set of characters.
`static int`	`indexOfAny(CharSequence str, CharSequence... searchStrs)` Find the first index of any of a set of potential substrings.
`static int`	`indexOfAny(CharSequence cs, String searchChars)` Search a CharSequence to find the first index of any character in the given set of characters.
`static int`	`indexOfAnyBut(CharSequence cs, char... searchChars)` Searches a CharSequence to find the first index of any character not in the given set of characters.
`static int`	`indexOfAnyBut(CharSequence seq, CharSequence searchChars)` Search a CharSequence to find the first index of any character not in the given set of characters.
`static int`	`indexOfDifference(CharSequence... css)` Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.
`static int`	`indexOfDifference(CharSequence cs1, CharSequence cs2)` Compares two CharSequences, and returns the index at which the CharSequences begin to differ.
`static int`	`indexOfIgnoreCase(CharSequence str, CharSequence searchStr)` Case in-sensitive find of the first index within a CharSequence.
`static int`	`indexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)` Case in-sensitive find of the first index within a CharSequence from the specified position.
`static boolean`	`isAllLowerCase(CharSequence cs)` Checks if the CharSequence contains only lowercase characters.
`static boolean`	`isAllUpperCase(CharSequence cs)` Checks if the CharSequence contains only uppercase characters.
`static boolean`	`isAlpha(CharSequence cs)` Checks if the CharSequence contains only Unicode letters.
`static boolean`	`isAlphanumeric(CharSequence cs)` Checks if the CharSequence contains only Unicode letters or digits.
`static boolean`	`isAlphanumericSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode letters, digits or space (`' '`).
`static boolean`	`isAlphaSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode letters and space (' ').
`static boolean`	`isAnyBlank(CharSequence... css)` Checks if any one of the CharSequences are blank ("") or null and not whitespace only..
`static boolean`	`isAnyEmpty(CharSequence... css)` Checks if any one of the CharSequences are empty ("") or null.
`static boolean`	`isAsciiPrintable(CharSequence cs)` Checks if the CharSequence contains only ASCII printable characters.
`static boolean`	`isBlank(CharSequence cs)` Checks if a CharSequence is whitespace, empty ("") or null.
`static boolean`	`isEmpty(CharSequence cs)` Checks if a CharSequence is empty ("") or null.
`static boolean`	`isNoneBlank(CharSequence... css)` Checks if none of the CharSequences are blank ("") or null and whitespace only..
`static boolean`	`isNoneEmpty(CharSequence... css)` Checks if none of the CharSequences are empty ("") or null.
`static boolean`	`isNotBlank(CharSequence cs)` Checks if a CharSequence is not empty (""), not null and not whitespace only.
`static boolean`	`isNotEmpty(CharSequence cs)` Checks if a CharSequence is not empty ("") and not null.
`static boolean`	`isNumeric(CharSequence cs)` Checks if the CharSequence contains only Unicode digits.
`static boolean`	`isNumericSpace(CharSequence cs)` Checks if the CharSequence contains only Unicode digits or space (`' '`).
`static boolean`	`isWhitespace(CharSequence cs)` Checks if the CharSequence contains only whitespace.
`static String`	`join(byte[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(byte[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(char[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(char[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(double[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(double[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(float[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(float[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(int[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(int[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Iterable<?> iterable, char separator)` Joins the elements of the provided `Iterable` into a single String containing the provided elements.
`static String`	`join(Iterable<?> iterable, String separator)` Joins the elements of the provided `Iterable` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, char separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, String separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(long[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(long[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(short[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(short[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static <T> String`	`join(T... elements)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static int`	`lastIndexOf(CharSequence seq, CharSequence searchSeq)` Finds the last index within a CharSequence, handling `null`.
`static int`	`lastIndexOf(CharSequence seq, CharSequence searchSeq, int startPos)` Finds the last index within a CharSequence, handling `null`.
`static int`	`lastIndexOf(CharSequence seq, int searchChar)` Finds the last index within a CharSequence, handling `null`.
`static int`	`lastIndexOf(CharSequence seq, int searchChar, int startPos)` Finds the last index within a CharSequence from a start position, handling `null`.
`static int`	`lastIndexOfAny(CharSequence str, CharSequence... searchStrs)` Find the latest index of any of a set of potential substrings.
`static int`	`lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr)` Case in-sensitive find of the last index within a CharSequence.
`static int`	`lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)` Case in-sensitive find of the last index within a CharSequence from the specified position.
`static int`	`lastOrdinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)` Finds the n-th last index within a String, handling `null`.
`static String`	`left(String str, int len)` Gets the leftmost `len` characters of a String.
`static String`	`leftPad(String str, int size)` Left pad a String with spaces (' ').
`static String`	`leftPad(String str, int size, char padChar)` Left pad a String with a specified character.
`static String`	`leftPad(String str, int size, String padStr)` Left pad a String with a specified String.
`static int`	`length(CharSequence cs)` Gets a CharSequence length or `0` if the CharSequence is `null`.
`static String`	`lowerCase(String str)` Converts a String to lower case as per `String.toLowerCase()`.
`static String`	`mid(String str, int pos, int len)` Gets `len` characters from the middle of a String.
`static String`	`normalizeSpace(String str)` Similar to http://www.w3.org/TR/xpath /#function-normalize -space
`static int`	`ordinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)` Finds the n-th index within a CharSequence, handling `null`.
`static String`	`overlay(String str, String overlay, int start, int end)` Overlays part of a String with another String.
`static String`	`prependIfMissing(String str, CharSequence prefix, CharSequence... prefixes)` Prepends the prefix to the start of the string if the string does not already start with any of the prefixes.
`static String`	`prependIfMissingIgnoreCase(String str, CharSequence prefix, CharSequence... prefixes)` Prepends the prefix to the start of the string if the string does not already start, case insensitive, with any of the prefixes.
`static String`	`remove(String str, char remove)` Removes all occurrences of a character from within the source string.
`static String`	`remove(String str, String remove)` Removes all occurrences of a substring from within the source string.
`static String`	`removeEnd(String str, String remove)` Removes a substring only if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeEndIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeStart(String str, String remove)` Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.
`static String`	`removeStartIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.
`static String`	`repeat(char ch, int repeat)` Returns padding using the specified delimiter repeated to a given length.
`static String`	`repeat(String str, int repeat)` Repeat a String `repeat` times to form a new String.
`static String`	`repeat(String str, String separator, int repeat)` Repeat a String `repeat` times to form a new String, with a String separator injected each time.
`static String`	`replace(String text, String searchString, String replacement)` Replaces all occurrences of a String within another String.
`static String`	`replace(String text, String searchString, String replacement, int max)` Replaces a String with another String inside a larger String, for the first `max` values of the search String.
`static String`	`replaceChars(String str, char searchChar, char replaceChar)` Replaces all occurrences of a character in a String with another.
`static String`	`replaceChars(String str, String searchChars, String replaceChars)` Replaces multiple characters in a String in one go.
`static String`	`replaceEach(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceEachRepeatedly(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceOnce(String text, String searchString, String replacement)` Replaces a String with another String inside a larger String, once.
`static String`	`reverse(String str)` Reverses a String as per `StringBuilder.reverse()`.
`static String`	`reverseDelimited(String str, char separatorChar)` Reverses a String that is delimited by a specific character.
`static String`	`right(String str, int len)` Gets the rightmost `len` characters of a String.
`static String`	`rightPad(String str, int size)` Right pad a String with spaces (' ').
`static String`	`rightPad(String str, int size, char padChar)` Right pad a String with a specified character.
`static String`	`rightPad(String str, int size, String padStr)` Right pad a String with a specified String.
`static String[]`	`split(String str)` Splits the provided text into an array, using whitespace as the separator.
`static String[]`	`split(String str, char separatorChar)` Splits the provided text into an array, separator specified.
`static String[]`	`split(String str, String separatorChars)` Splits the provided text into an array, separators specified.
`static String[]`	`split(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified.
`static String[]`	`splitByWholeSeparator(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparator(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitPreserveAllTokens(String str)` Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, char separatorChar)` Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars)` Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static boolean`	`startsWith(CharSequence str, CharSequence prefix)` Check if a CharSequence starts with a specified prefix.
`static boolean`	`startsWithAny(CharSequence string, CharSequence... searchStrings)` Check if a CharSequence starts with any of an array of specified strings.
`static boolean`	`startsWithIgnoreCase(CharSequence str, CharSequence prefix)` Case insensitive check if a CharSequence starts with a specified prefix.
`static String`	`strip(String str)` Strips whitespace from the start and end of a String.
`static String`	`strip(String str, String stripChars)` Strips any of a set of characters from the start and end of a String.
`static String[]`	`stripAll(String... strs)` Strips whitespace from the start and end of every String in an array.
`static String[]`	`stripAll(String[] strs, String stripChars)` Strips any of a set of characters from the start and end of every String in an array.
`static String`	`stripEnd(String str, String stripChars)` Strips any of a set of characters from the end of a String.
`static String`	`stripStart(String str, String stripChars)` Strips any of a set of characters from the start of a String.
`static String`	`stripToEmpty(String str)` Strips whitespace from the start and end of a String returning an empty String if `null` input.
`static String`	`stripToNull(String str)` Strips whitespace from the start and end of a String returning `null` if the String is empty ("") after the strip.
`static String`	`substring(String str, int start)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substring(String str, int start, int end)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substringAfter(String str, String separator)` Gets the substring after the first occurrence of a separator.
`static String`	`substringAfterLast(String str, String separator)` Gets the substring after the last occurrence of a separator.
`static String`	`substringBefore(String str, String separator)` Gets the substring before the first occurrence of a separator.
`static String`	`substringBeforeLast(String str, String separator)` Gets the substring before the last occurrence of a separator.
`static String`	`substringBetween(String str, String tag)` Gets the String that is nested in between two instances of the same String.
`static String`	`substringBetween(String str, String open, String close)` Gets the String that is nested in between two Strings.
`static String[]`	`substringsBetween(String str, String open, String close)` Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.
`static String`	`trim(String str)` Removes control characters (char <= 32) from both ends of this String, handling `null` by returning `null`.
`static String`	`trimToEmpty(String str)` Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is `null`.
`static String`	`trimToNull(String str)` Removes control characters (char <= 32) from both ends of this String returning `null` if the String is empty ("") after the trim or if it is `null`.
`static String`	`uncapitalize(String str)` Uncapitalizes a String changing the first letter to title case as per `Character.toLowerCase(char)`.
`static String`	`upperCase(String str)` Converts a String to upper case as per `String.toUpperCase()`.
`static String`	`wrap(String str, char wrapWith)` Wraps a string with a char.
`static String`	`wrap(String str, String wrapWith)` Wraps a String with another String.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - SPACE
```
public static final String SPACE
```
    A String for a space character.
    
    Since:
    
    3.2
    
    See Also:
    Constant Field Values
  - EMPTY
```
public static final String EMPTY
```
    The empty String "".
    
    Since:
    
    2.0
    
    See Also:
    Constant Field Values
  - LF
```
public static final String LF
```
    A String for linefeed LF ("\n").
    
    Since:
    
    3.2
    
    See Also:
    JLF: Escape Sequences for Character and String Literals, Constant Field Values
  - CR
```
public static final String CR
```
    A String for carriage return CR ("\r").
    
    Since:
    
    3.2
    
    See Also:
    JLF: Escape Sequences for Character and String Literals, Constant Field Values
  - INDEX_NOT_FOUND
```
public static final int INDEX_NOT_FOUND
```
    Represents a failed index search.
    
    Since:
    
    2.1
    
    See Also:
    Constant Field Values
- Constructor Detail
  - StringUtils
```
public StringUtils()
```
    StringUtils instances should NOT be constructed in standard programming. Instead, the class should be used as StringUtils.trim(" foo ");.
    
    This constructor is public to permit tools that require a JavaBean instance to operate.
- Method Detail
  - isEmpty
```
public static boolean isEmpty(CharSequence cs)
```
    Checks if a CharSequence is empty ("") or null.
```
 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false
 
```
    NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if the CharSequence is empty or null
    Since:
    
    3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
  - isNotEmpty
```
public static boolean isNotEmpty(CharSequence cs)
```
    Checks if a CharSequence is not empty ("") and not null.
```
 StringUtils.isNotEmpty(null)      = false
 StringUtils.isNotEmpty("")        = false
 StringUtils.isNotEmpty(" ")       = true
 StringUtils.isNotEmpty("bob")     = true
 StringUtils.isNotEmpty("  bob  ") = true
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if the CharSequence is not empty and not null
    Since:
    
    3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
  - isAnyEmpty
```
public static boolean isAnyEmpty(CharSequence... css)
```
    Checks if any one of the CharSequences are empty ("") or null.
```
 StringUtils.isAnyEmpty(null)             = true
 StringUtils.isAnyEmpty(null, "foo")      = true
 StringUtils.isAnyEmpty("", "bar")        = true
 StringUtils.isAnyEmpty("bob", "")        = true
 StringUtils.isAnyEmpty("  bob  ", null)  = true
 StringUtils.isAnyEmpty(" ", "bar")       = false
 StringUtils.isAnyEmpty("foo", "bar")     = false
 
```
    Parameters:
    css - the CharSequences to check, may be null or empty
    
    Returns:
    true if any of the CharSequences are empty or null
    Since:
    
    3.2
  - isNoneEmpty
```
public static boolean isNoneEmpty(CharSequence... css)
```
    Checks if none of the CharSequences are empty ("") or null.
```
 StringUtils.isNoneEmpty(null)             = false
 StringUtils.isNoneEmpty(null, "foo")      = false
 StringUtils.isNoneEmpty("", "bar")        = false
 StringUtils.isNoneEmpty("bob", "")        = false
 StringUtils.isNoneEmpty("  bob  ", null)  = false
 StringUtils.isNoneEmpty(" ", "bar")       = true
 StringUtils.isNoneEmpty("foo", "bar")     = true
 
```
    Parameters:
    css - the CharSequences to check, may be null or empty
    
    Returns:
    true if none of the CharSequences are empty or null
    Since:
    
    3.2
  - isBlank
```
public static boolean isBlank(CharSequence cs)
```
    Checks if a CharSequence is whitespace, empty ("") or null.
```
 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if the CharSequence is null, empty or whitespace
    Since:
    
    2.0, 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)
  - isNotBlank
```
public static boolean isNotBlank(CharSequence cs)
```
    Checks if a CharSequence is not empty (""), not null and not whitespace only.
```
 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if the CharSequence is not empty and not null and not whitespace
    Since:
    
    2.0, 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
  - isAnyBlank
```
public static boolean isAnyBlank(CharSequence... css)
```
    Checks if any one of the CharSequences are blank ("") or null and not whitespace only..
```
 StringUtils.isAnyBlank(null)             = true
 StringUtils.isAnyBlank(null, "foo")      = true
 StringUtils.isAnyBlank(null, null)       = true
 StringUtils.isAnyBlank("", "bar")        = true
 StringUtils.isAnyBlank("bob", "")        = true
 StringUtils.isAnyBlank("  bob  ", null)  = true
 StringUtils.isAnyBlank(" ", "bar")       = true
 StringUtils.isAnyBlank("foo", "bar")     = false
 
```
    Parameters:
    css - the CharSequences to check, may be null or empty
    
    Returns:
    true if any of the CharSequences are blank or null or whitespace only
    Since:
    
    3.2
  - isNoneBlank
```
public static boolean isNoneBlank(CharSequence... css)
```
    Checks if none of the CharSequences are blank ("") or null and whitespace only..
```
 StringUtils.isNoneBlank(null)             = false
 StringUtils.isNoneBlank(null, "foo")      = false
 StringUtils.isNoneBlank(null, null)       = false
 StringUtils.isNoneBlank("", "bar")        = false
 StringUtils.isNoneBlank("bob", "")        = false
 StringUtils.isNoneBlank("  bob  ", null)  = false
 StringUtils.isNoneBlank(" ", "bar")       = false
 StringUtils.isNoneBlank("foo", "bar")     = true
 
```
    Parameters:
    css - the CharSequences to check, may be null or empty
    
    Returns:
    true if none of the CharSequences are blank or null or whitespace only
    Since:
    
    3.2
  - trim
```
public static String trim(String str)
```
    Removes control characters (char <= 32) from both ends of this String, handling null by returning null.
    
    The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use strip(String).
    
    To trim your choice of characters, use the strip(String, String) methods.
```
 StringUtils.trim(null)          = null
 StringUtils.trim("")            = ""
 StringUtils.trim("     ")       = ""
 StringUtils.trim("abc")         = "abc"
 StringUtils.trim("    abc    ") = "abc"
 
```
    Parameters:
    str - the String to be trimmed, may be null
    
    Returns:
    the trimmed string, null if null String input
  - trimToNull
```
public static String trimToNull(String str)
```
    Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.
    The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToNull(String).
```
 StringUtils.trimToNull(null)          = null
 StringUtils.trimToNull("")            = null
 StringUtils.trimToNull("     ")       = null
 StringUtils.trimToNull("abc")         = "abc"
 StringUtils.trimToNull("    abc    ") = "abc"
 
```
    Parameters:
    str - the String to be trimmed, may be null
    
    Returns:
    the trimmed String, null if only chars <= 32, empty or null String input
    Since:
    
    2.0
  - trimToEmpty
```
public static String trimToEmpty(String str)
```
    Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.
    The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToEmpty(String).
```
 StringUtils.trimToEmpty(null)          = ""
 StringUtils.trimToEmpty("")            = ""
 StringUtils.trimToEmpty("     ")       = ""
 StringUtils.trimToEmpty("abc")         = "abc"
 StringUtils.trimToEmpty("    abc    ") = "abc"
 
```
    Parameters:
    str - the String to be trimmed, may be null
    
    Returns:
    the trimmed String, or an empty String if null input
    Since:
    
    2.0
  - strip
```
public static String strip(String str)
```
    Strips whitespace from the start and end of a String.
    
    This is similar to trim(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).
    
    A null input String returns null.
```
 StringUtils.strip(null)     = null
 StringUtils.strip("")       = ""
 StringUtils.strip("   ")    = ""
 StringUtils.strip("abc")    = "abc"
 StringUtils.strip("  abc")  = "abc"
 StringUtils.strip("abc  ")  = "abc"
 StringUtils.strip(" abc ")  = "abc"
 StringUtils.strip(" ab c ") = "ab c"
 
```
    Parameters:
    str - the String to remove whitespace from, may be null
    
    Returns:
    the stripped String, null if null String input
  - stripToNull
```
public static String stripToNull(String str)
```
    Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.
    
    This is similar to trimToNull(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).
```
 StringUtils.stripToNull(null)     = null
 StringUtils.stripToNull("")       = null
 StringUtils.stripToNull("   ")    = null
 StringUtils.stripToNull("abc")    = "abc"
 StringUtils.stripToNull("  abc")  = "abc"
 StringUtils.stripToNull("abc  ")  = "abc"
 StringUtils.stripToNull(" abc ")  = "abc"
 StringUtils.stripToNull(" ab c ") = "ab c"
 
```
    Parameters:
    str - the String to be stripped, may be null
    
    Returns:
    the stripped String, null if whitespace, empty or null String input
    Since:
    
    2.0
  - stripToEmpty
```
public static String stripToEmpty(String str)
```
    Strips whitespace from the start and end of a String returning an empty String if null input.
    
    This is similar to trimToEmpty(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).
```
 StringUtils.stripToEmpty(null)     = ""
 StringUtils.stripToEmpty("")       = ""
 StringUtils.stripToEmpty("   ")    = ""
 StringUtils.stripToEmpty("abc")    = "abc"
 StringUtils.stripToEmpty("  abc")  = "abc"
 StringUtils.stripToEmpty("abc  ")  = "abc"
 StringUtils.stripToEmpty(" abc ")  = "abc"
 StringUtils.stripToEmpty(" ab c ") = "ab c"
 
```
    Parameters:
    str - the String to be stripped, may be null
    
    Returns:
    the trimmed String, or an empty String if null input
    Since:
    
    2.0
  - strip
```
public static String strip(String str,
           String stripChars)
```
    Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.
    
    A null input String returns null. An empty string ("") input returns the empty string.
    
    If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char). Alternatively use strip(String).
```
 StringUtils.strip(null, *)          = null
 StringUtils.strip("", *)            = ""
 StringUtils.strip("abc", null)      = "abc"
 StringUtils.strip("  abc", null)    = "abc"
 StringUtils.strip("abc  ", null)    = "abc"
 StringUtils.strip(" abc ", null)    = "abc"
 StringUtils.strip("  abcyx", "xyz") = "  abc"
 
```
    Parameters:
    str - the String to remove characters from, may be null
    stripChars - the characters to remove, null treated as whitespace
    
    Returns:
    the stripped String, null if null String input
  - stripStart
```
public static String stripStart(String str,
                String stripChars)
```
    Strips any of a set of characters from the start of a String.
    
    A null input String returns null. An empty string ("") input returns the empty string.
    
    If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).
```
 StringUtils.stripStart(null, *)          = null
 StringUtils.stripStart("", *)            = ""
 StringUtils.stripStart("abc", "")        = "abc"
 StringUtils.stripStart("abc", null)      = "abc"
 StringUtils.stripStart("  abc", null)    = "abc"
 StringUtils.stripStart("abc  ", null)    = "abc  "
 StringUtils.stripStart(" abc ", null)    = "abc "
 StringUtils.stripStart("yxabc  ", "xyz") = "abc  "
 
```
    Parameters:
    str - the String to remove characters from, may be null
    stripChars - the characters to remove, null treated as whitespace
    
    Returns:
    the stripped String, null if null String input
  - stripEnd
```
public static String stripEnd(String str,
              String stripChars)
```
    Strips any of a set of characters from the end of a String.
    
    A null input String returns null. An empty string ("") input returns the empty string.
    
    If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).
```
 StringUtils.stripEnd(null, *)          = null
 StringUtils.stripEnd("", *)            = ""
 StringUtils.stripEnd("abc", "")        = "abc"
 StringUtils.stripEnd("abc", null)      = "abc"
 StringUtils.stripEnd("  abc", null)    = "  abc"
 StringUtils.stripEnd("abc  ", null)    = "abc"
 StringUtils.stripEnd(" abc ", null)    = " abc"
 StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
 StringUtils.stripEnd("120.00", ".0")   = "12"
 
```
    Parameters:
    str - the String to remove characters from, may be null
    stripChars - the set of characters to remove, null treated as whitespace
    
    Returns:
    the stripped String, null if null String input
  - stripAll
```
public static String[] stripAll(String... strs)
```
    Strips whitespace from the start and end of every String in an array. Whitespace is defined by Character.isWhitespace(char).
    
    A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored.
```
 StringUtils.stripAll(null)             = null
 StringUtils.stripAll([])               = []
 StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null])  = ["abc", null]
 
```
    Parameters:
    strs - the array to remove whitespace from, may be null
    
    Returns:
    the stripped Strings, null if null array input
  - stripAll
```
public static String[] stripAll(String[] strs,
                String stripChars)
```
    Strips any of a set of characters from the start and end of every String in an array.
    
    Whitespace is defined by Character.isWhitespace(char).
    
    A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored. A null stripChars will strip whitespace as defined by Character.isWhitespace(char).
```
 StringUtils.stripAll(null, *)                = null
 StringUtils.stripAll([], *)                  = []
 StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
 StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
 StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
 
```
    Parameters:
    strs - the array to remove characters from, may be null
    stripChars - the characters to remove, null treated as whitespace
    
    Returns:
    the stripped Strings, null if null array input
  - equals
```
public static boolean equals(CharSequence cs1,
             CharSequence cs2)
```
    Compares two CharSequences, returning true if they represent equal sequences of characters.
    
    nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.equals(null, null)   = true
 StringUtils.equals(null, "abc")  = false
 StringUtils.equals("abc", null)  = false
 StringUtils.equals("abc", "abc") = true
 StringUtils.equals("abc", "ABC") = false
 
```
    Parameters:
    cs1 - the first CharSequence, may be null
    cs2 - the second CharSequence, may be null
    
    Returns:
    true if the CharSequences are equal (case-sensitive), or both null
    Since:
    
    3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)
    
    See Also:
    Object.equals(Object)
  - equalsIgnoreCase
```
public static boolean equalsIgnoreCase(CharSequence str1,
                       CharSequence str2)
```
    Compares two CharSequences, returning true if they represent equal sequences of characters, ignoring case.
    
    nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.
```
 StringUtils.equalsIgnoreCase(null, null)   = true
 StringUtils.equalsIgnoreCase(null, "abc")  = false
 StringUtils.equalsIgnoreCase("abc", null)  = false
 StringUtils.equalsIgnoreCase("abc", "abc") = true
 StringUtils.equalsIgnoreCase("abc", "ABC") = true
 
```
    Parameters:
    str1 - the first CharSequence, may be null
    str2 - the second CharSequence, may be null
    
    Returns:
    true if the CharSequence are equal, case insensitive, or both null
    Since:
    
    3.0 Changed signature from equalsIgnoreCase(String, String) to equalsIgnoreCase(CharSequence, CharSequence)
  - indexOf
```
public static int indexOf(CharSequence seq,
          int searchChar)
```
    Finds the first index within a CharSequence, handling null. This method uses String.indexOf(int, int) if possible.
    
    A null or empty ("") CharSequence will return INDEX_NOT_FOUND (-1).
```
 StringUtils.indexOf(null, *)         = -1
 StringUtils.indexOf("", *)           = -1
 StringUtils.indexOf("aabaabaa", 'a') = 0
 StringUtils.indexOf("aabaabaa", 'b') = 2
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChar - the character to find
    
    Returns:
    the first index of the search character, -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from indexOf(String, int) to indexOf(CharSequence, int)
  - indexOf
```
public static int indexOf(CharSequence seq,
          int searchChar,
          int startPos)
```
    Finds the first index within a CharSequence from a start position, handling null. This method uses String.indexOf(int, int) if possible.
    
    A null or empty ("") CharSequence will return (INDEX_NOT_FOUND) -1. A negative start position is treated as zero. A start position greater than the string length returns -1.
```
 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf("", *, *)            = -1
 StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
 StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
 StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
 StringUtils.indexOf("aabaabaa", 'b', -1) = 2
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChar - the character to find
    startPos - the start position, negative treated as zero
    
    Returns:
    the first index of the search character (always ≥ startPos), -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from indexOf(String, int, int) to indexOf(CharSequence, int, int)
  - indexOf
```
public static int indexOf(CharSequence seq,
          CharSequence searchSeq)
```
    Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.
    
    A null CharSequence will return -1.
```
 StringUtils.indexOf(null, *)          = -1
 StringUtils.indexOf(*, null)          = -1
 StringUtils.indexOf("", "")           = 0
 StringUtils.indexOf("", *)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a")  = 0
 StringUtils.indexOf("aabaabaa", "b")  = 2
 StringUtils.indexOf("aabaabaa", "ab") = 1
 StringUtils.indexOf("aabaabaa", "")   = 0
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchSeq - the CharSequence to find, may be null
    
    Returns:
    the first index of the search CharSequence, -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from indexOf(String, String) to indexOf(CharSequence, CharSequence)
  - indexOf
```
public static int indexOf(CharSequence seq,
          CharSequence searchSeq,
          int startPos)
```
    Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.
    
    A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.
```
 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf(*, null, *)          = -1
 StringUtils.indexOf("", "", 0)           = 0
 StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a", 0)  = 0
 StringUtils.indexOf("aabaabaa", "b", 0)  = 2
 StringUtils.indexOf("aabaabaa", "ab", 0) = 1
 StringUtils.indexOf("aabaabaa", "b", 3)  = 5
 StringUtils.indexOf("aabaabaa", "b", 9)  = -1
 StringUtils.indexOf("aabaabaa", "b", -1) = 2
 StringUtils.indexOf("aabaabaa", "", 2)   = 2
 StringUtils.indexOf("abc", "", 9)        = 3
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchSeq - the CharSequence to find, may be null
    startPos - the start position, negative treated as zero
    
    Returns:
    the first index of the search CharSequence (always ≥ startPos), -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from indexOf(String, String, int) to indexOf(CharSequence, CharSequence, int)
  - ordinalIndexOf
```
public static int ordinalIndexOf(CharSequence str,
                 CharSequence searchStr,
                 int ordinal)
```
    Finds the n-th index within a CharSequence, handling null. This method uses String.indexOf(String) if possible.
    
    A null CharSequence will return -1.
```
 StringUtils.ordinalIndexOf(null, *, *)          = -1
 StringUtils.ordinalIndexOf(*, null, *)          = -1
 StringUtils.ordinalIndexOf("", "", *)           = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
 StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
 StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
 StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
 StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0
 
```
    Note that 'head(CharSequence str, int n)' may be implemented as:
```
 str.substring(0, lastOrdinalIndexOf(str, "\n", n))
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    ordinal - the n-th searchStr to find
    
    Returns:
    the n-th index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
    Since:
    
    2.1, 3.0 Changed signature from ordinalIndexOf(String, String, int) to ordinalIndexOf(CharSequence, CharSequence, int)
  - indexOfIgnoreCase
```
public static int indexOfIgnoreCase(CharSequence str,
                    CharSequence searchStr)
```
    Case in-sensitive find of the first index within a CharSequence.
    
    A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.
```
 StringUtils.indexOfIgnoreCase(null, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null)          = -1
 StringUtils.indexOfIgnoreCase("", "")           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    
    Returns:
    the first index of the search CharSequence, -1 if no match or null string input
    Since:
    
    2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String) to indexOfIgnoreCase(CharSequence, CharSequence)
  - indexOfIgnoreCase
```
public static int indexOfIgnoreCase(CharSequence str,
                    CharSequence searchStr,
                    int startPos)
```
    Case in-sensitive find of the first index within a CharSequence from the specified position.
    
    A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.
```
 StringUtils.indexOfIgnoreCase(null, *, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null, *)          = -1
 StringUtils.indexOfIgnoreCase("", "", 0)           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
 StringUtils.indexOfIgnoreCase("abc", "", 9)        = 3
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    startPos - the start position, negative treated as zero
    
    Returns:
    the first index of the search CharSequence (always ≥ startPos), -1 if no match or null string input
    Since:
    
    2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String, int) to indexOfIgnoreCase(CharSequence, CharSequence, int)
  - lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
              int searchChar)
```
    Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(int) if possible.
    
    A null or empty ("") CharSequence will return -1.
```
 StringUtils.lastIndexOf(null, *)         = -1
 StringUtils.lastIndexOf("", *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'a') = 7
 StringUtils.lastIndexOf("aabaabaa", 'b') = 5
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChar - the character to find
    
    Returns:
    the last index of the search character, -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from lastIndexOf(String, int) to lastIndexOf(CharSequence, int)
  - lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
              int searchChar,
              int startPos)
```
    Finds the last index within a CharSequence from a start position, handling null. This method uses String.lastIndexOf(int, int) if possible.
    
    A null or empty ("") CharSequence will return -1. A negative start position returns -1. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
```
 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf("", *,  *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
 StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
 StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChar - the character to find
    startPos - the start position
    
    Returns:
    the last index of the search character (always ≤ startPos), -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from lastIndexOf(String, int, int) to lastIndexOf(CharSequence, int, int)
  - lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
              CharSequence searchSeq)
```
    Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(String) if possible.
    
    A null CharSequence will return -1.
```
 StringUtils.lastIndexOf(null, *)          = -1
 StringUtils.lastIndexOf(*, null)          = -1
 StringUtils.lastIndexOf("", "")           = 0
 StringUtils.lastIndexOf("aabaabaa", "a")  = 7
 StringUtils.lastIndexOf("aabaabaa", "b")  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab") = 4
 StringUtils.lastIndexOf("aabaabaa", "")   = 8
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchSeq - the CharSequence to find, may be null
    
    Returns:
    the last index of the search String, -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from lastIndexOf(String, String) to lastIndexOf(CharSequence, CharSequence)
  - lastOrdinalIndexOf
```
public static int lastOrdinalIndexOf(CharSequence str,
                     CharSequence searchStr,
                     int ordinal)
```
    Finds the n-th last index within a String, handling null. This method uses String.lastIndexOf(String).
    
    A null String will return -1.
```
 StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
 StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
 StringUtils.lastOrdinalIndexOf("", "", *)           = 0
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8
 
```
    Note that 'tail(CharSequence str, int n)' may be implemented as:
```
 str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    ordinal - the n-th last searchStr to find
    
    Returns:
    the n-th last index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
    Since:
    
    2.5, 3.0 Changed signature from lastOrdinalIndexOf(String, String, int) to lastOrdinalIndexOf(CharSequence, CharSequence, int)
  - lastIndexOf
```
public static int lastIndexOf(CharSequence seq,
              CharSequence searchSeq,
              int startPos)
```
    Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(String, int) if possible.
    
    A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
```
 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf(*, null, *)          = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
 StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
 StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
 StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", "b", 1)  = -1
 StringUtils.lastIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastIndexOf("aabaabaa", "ba", 2)  = -1
 StringUtils.lastIndexOf("aabaabaa", "ba", 2)  = 2
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchSeq - the CharSequence to find, may be null
    startPos - the start position, negative treated as zero
    
    Returns:
    the last index of the search CharSequence (always ≤ startPos), -1 if no match or null string input
    Since:
    
    2.0, 3.0 Changed signature from lastIndexOf(String, String, int) to lastIndexOf(CharSequence, CharSequence, int)
  - lastIndexOfIgnoreCase
```
public static int lastIndexOfIgnoreCase(CharSequence str,
                        CharSequence searchStr)
```
    Case in-sensitive find of the last index within a CharSequence.
    
    A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string.
```
 StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    
    Returns:
    the first index of the search CharSequence, -1 if no match or null string input
    Since:
    
    2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String) to lastIndexOfIgnoreCase(CharSequence, CharSequence)
  - lastIndexOfIgnoreCase
```
public static int lastIndexOfIgnoreCase(CharSequence str,
                        CharSequence searchStr,
                        int startPos)
```
    Case in-sensitive find of the last index within a CharSequence from the specified position.
    
    A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string. The search starts at the startPos and works backwards; matches starting after the start position are ignored.
```
 StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    startPos - the start position
    
    Returns:
    the last index of the search CharSequence (always ≤ startPos), -1 if no match or null input
    Since:
    
    2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String, int) to lastIndexOfIgnoreCase(CharSequence, CharSequence, int)
  - contains
```
public static boolean contains(CharSequence seq,
               int searchChar)
```
    Checks if CharSequence contains a search character, handling null. This method uses String.indexOf(int) if possible.
    
    A null or empty ("") CharSequence will return false.
```
 StringUtils.contains(null, *)    = false
 StringUtils.contains("", *)      = false
 StringUtils.contains("abc", 'a') = true
 StringUtils.contains("abc", 'z') = false
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChar - the character to find
    
    Returns:
    true if the CharSequence contains the search character, false if not or null string input
    Since:
    
    2.0, 3.0 Changed signature from contains(String, int) to contains(CharSequence, int)
  - contains
```
public static boolean contains(CharSequence seq,
               CharSequence searchSeq)
```
    Checks if CharSequence contains a search CharSequence, handling null. This method uses String.indexOf(String) if possible.
    
    A null CharSequence will return false.
```
 StringUtils.contains(null, *)     = false
 StringUtils.contains(*, null)     = false
 StringUtils.contains("", "")      = true
 StringUtils.contains("abc", "")   = true
 StringUtils.contains("abc", "a")  = true
 StringUtils.contains("abc", "z")  = false
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchSeq - the CharSequence to find, may be null
    
    Returns:
    true if the CharSequence contains the search CharSequence, false if not or null string input
    Since:
    
    2.0, 3.0 Changed signature from contains(String, String) to contains(CharSequence, CharSequence)
  - containsIgnoreCase
```
public static boolean containsIgnoreCase(CharSequence str,
                         CharSequence searchStr)
```
    Checks if CharSequence contains a search CharSequence irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).
    A null CharSequence will return false.
```
 StringUtils.contains(null, *) = false
 StringUtils.contains(*, null) = false
 StringUtils.contains("", "") = true
 StringUtils.contains("abc", "") = true
 StringUtils.contains("abc", "a") = true
 StringUtils.contains("abc", "z") = false
 StringUtils.contains("abc", "A") = true
 StringUtils.contains("abc", "Z") = false
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStr - the CharSequence to find, may be null
    
    Returns:
    true if the CharSequence contains the search CharSequence irrespective of case or false if not or null string input
    Since:
    
    3.0 Changed signature from containsIgnoreCase(String, String) to containsIgnoreCase(CharSequence, CharSequence)
  - containsWhitespace
```
public static boolean containsWhitespace(CharSequence seq)
```
    Check whether the given CharSequence contains any whitespace characters.
    
    Parameters:
    seq - the CharSequence to check (may be null)
    
    Returns:
    true if the CharSequence is not empty and contains at least 1 whitespace character
    Since:
    
    3.0
    
    See Also:
    Character.isWhitespace(char)
  - indexOfAny
```
public static int indexOfAny(CharSequence cs,
             char... searchChars)
```
    Search a CharSequence to find the first index of any character in the given set of characters.
    
    A null String will return -1. A null or zero length search array will return -1.
```
 StringUtils.indexOfAny(null, *)                = -1
 StringUtils.indexOfAny("", *)                  = -1
 StringUtils.indexOfAny(*, null)                = -1
 StringUtils.indexOfAny(*, [])                  = -1
 StringUtils.indexOfAny("zzabyycdxx",['z','a']) = 0
 StringUtils.indexOfAny("zzabyycdxx",['b','y']) = 3
 StringUtils.indexOfAny("aba", ['z'])           = -1
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the index of any of the chars, -1 if no match or null input
    Since:
    
    2.0, 3.0 Changed signature from indexOfAny(String, char[]) to indexOfAny(CharSequence, char...)
  - indexOfAny
```
public static int indexOfAny(CharSequence cs,
             String searchChars)
```
    Search a CharSequence to find the first index of any character in the given set of characters.
    
    A null String will return -1. A null search string will return -1.
```
 StringUtils.indexOfAny(null, *)            = -1
 StringUtils.indexOfAny("", *)              = -1
 StringUtils.indexOfAny(*, null)            = -1
 StringUtils.indexOfAny(*, "")              = -1
 StringUtils.indexOfAny("zzabyycdxx", "za") = 0
 StringUtils.indexOfAny("zzabyycdxx", "by") = 3
 StringUtils.indexOfAny("aba","z")          = -1
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the index of any of the chars, -1 if no match or null input
    Since:
    
    2.0, 3.0 Changed signature from indexOfAny(String, String) to indexOfAny(CharSequence, String)
  - containsAny
```
public static boolean containsAny(CharSequence cs,
                  char... searchChars)
```
    Checks if the CharSequence contains any character in the given set of characters.
    
    A null CharSequence will return false. A null or zero length search array will return false.
```
 StringUtils.containsAny(null, *)                = false
 StringUtils.containsAny("", *)                  = false
 StringUtils.containsAny(*, null)                = false
 StringUtils.containsAny(*, [])                  = false
 StringUtils.containsAny("zzabyycdxx",['z','a']) = true
 StringUtils.containsAny("zzabyycdxx",['b','y']) = true
 StringUtils.containsAny("aba", ['z'])           = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the true if any of the chars are found, false if no match or null input
    Since:
    
    2.4, 3.0 Changed signature from containsAny(String, char[]) to containsAny(CharSequence, char...)
  - containsAny
```
public static boolean containsAny(CharSequence cs,
                  CharSequence searchChars)
```
    Checks if the CharSequence contains any character in the given set of characters.
    
    A null CharSequence will return false. A null search CharSequence will return false.
```
 StringUtils.containsAny(null, *)            = false
 StringUtils.containsAny("", *)              = false
 StringUtils.containsAny(*, null)            = false
 StringUtils.containsAny(*, "")              = false
 StringUtils.containsAny("zzabyycdxx", "za") = true
 StringUtils.containsAny("zzabyycdxx", "by") = true
 StringUtils.containsAny("aba","z")          = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the true if any of the chars are found, false if no match or null input
    Since:
    
    2.4, 3.0 Changed signature from containsAny(String, String) to containsAny(CharSequence, CharSequence)
  - indexOfAnyBut
```
public static int indexOfAnyBut(CharSequence cs,
                char... searchChars)
```
    Searches a CharSequence to find the first index of any character not in the given set of characters.
    
    A null CharSequence will return -1. A null or zero length search array will return -1.
```
 StringUtils.indexOfAnyBut(null, *)                              = -1
 StringUtils.indexOfAnyBut("", *)                                = -1
 StringUtils.indexOfAnyBut(*, null)                              = -1
 StringUtils.indexOfAnyBut(*, [])                                = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
 StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
 StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1
 
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the index of any of the chars, -1 if no match or null input
    Since:
    
    2.0, 3.0 Changed signature from indexOfAnyBut(String, char[]) to indexOfAnyBut(CharSequence, char...)
  - indexOfAnyBut
```
public static int indexOfAnyBut(CharSequence seq,
                CharSequence searchChars)
```
    Search a CharSequence to find the first index of any character not in the given set of characters.
    
    A null CharSequence will return -1. A null or empty search string will return -1.
```
 StringUtils.indexOfAnyBut(null, *)            = -1
 StringUtils.indexOfAnyBut("", *)              = -1
 StringUtils.indexOfAnyBut(*, null)            = -1
 StringUtils.indexOfAnyBut(*, "")              = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
 StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
 StringUtils.indexOfAnyBut("aba","ab")         = -1
 
```
    Parameters:
    seq - the CharSequence to check, may be null
    searchChars - the chars to search for, may be null
    
    Returns:
    the index of any of the chars, -1 if no match or null input
    Since:
    
    2.0, 3.0 Changed signature from indexOfAnyBut(String, String) to indexOfAnyBut(CharSequence, CharSequence)
  - containsOnly
```
public static boolean containsOnly(CharSequence cs,
                   char... valid)
```
    Checks if the CharSequence contains only certain characters.
    
    A null CharSequence will return false. A null valid character array will return false. An empty CharSequence (length()=0) always returns true.
```
 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", '')      = false
 StringUtils.containsOnly("abab", 'abc') = true
 StringUtils.containsOnly("ab1", 'abc')  = false
 StringUtils.containsOnly("abz", 'abc')  = false
 
```
    Parameters:
    cs - the String to check, may be null
    valid - an array of valid chars, may be null
    
    Returns:
    true if it only contains valid chars and is non-null
    Since:
    
    3.0 Changed signature from containsOnly(String, char[]) to containsOnly(CharSequence, char...)
  - containsOnly
```
public static boolean containsOnly(CharSequence cs,
                   String validChars)
```
    Checks if the CharSequence contains only certain characters.
    
    A null CharSequence will return false. A null valid character String will return false. An empty String (length()=0) always returns true.
```
 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", "")      = false
 StringUtils.containsOnly("abab", "abc") = true
 StringUtils.containsOnly("ab1", "abc")  = false
 StringUtils.containsOnly("abz", "abc")  = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    validChars - a String of valid chars, may be null
    
    Returns:
    true if it only contains valid chars and is non-null
    Since:
    
    2.0, 3.0 Changed signature from containsOnly(String, String) to containsOnly(CharSequence, String)
  - containsNone
```
public static boolean containsNone(CharSequence cs,
                   char... searchChars)
```
    Checks that the CharSequence does not contain certain characters.
    
    A null CharSequence will return true. A null invalid character array will return true. An empty CharSequence (length()=0) always returns true.
```
 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", '')      = true
 StringUtils.containsNone("abab", 'xyz') = true
 StringUtils.containsNone("ab1", 'xyz')  = true
 StringUtils.containsNone("abz", 'xyz')  = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    searchChars - an array of invalid chars, may be null
    
    Returns:
    true if it contains none of the invalid chars, or is null
    Since:
    
    2.0, 3.0 Changed signature from containsNone(String, char[]) to containsNone(CharSequence, char...)
  - containsNone
```
public static boolean containsNone(CharSequence cs,
                   String invalidChars)
```
    Checks that the CharSequence does not contain certain characters.
    
    A null CharSequence will return true. A null invalid character array will return true. An empty String ("") always returns true.
```
 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", "")      = true
 StringUtils.containsNone("abab", "xyz") = true
 StringUtils.containsNone("ab1", "xyz")  = true
 StringUtils.containsNone("abz", "xyz")  = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    invalidChars - a String of invalid chars, may be null
    
    Returns:
    true if it contains none of the invalid chars, or is null
    Since:
    
    2.0, 3.0 Changed signature from containsNone(String, String) to containsNone(CharSequence, String)
  - indexOfAny
```
public static int indexOfAny(CharSequence str,
             CharSequence... searchStrs)
```
    Find the first index of any of a set of potential substrings.
    
    A null CharSequence will return -1. A null or zero length search array will return -1. A null search array entry will be ignored, but a search array containing "" will return 0 if str is not null. This method uses String.indexOf(String) if possible.
```
 StringUtils.indexOfAny(null, *)                     = -1
 StringUtils.indexOfAny(*, null)                     = -1
 StringUtils.indexOfAny(*, [])                       = -1
 StringUtils.indexOfAny("zzabyycdxx", ["ab","cd"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["cd","ab"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["mn","op"])   = -1
 StringUtils.indexOfAny("zzabyycdxx", ["zab","aby"]) = 1
 StringUtils.indexOfAny("zzabyycdxx", [""])          = 0
 StringUtils.indexOfAny("", [""])                    = 0
 StringUtils.indexOfAny("", ["a"])                   = -1
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStrs - the CharSequences to search for, may be null
    
    Returns:
    the first index of any of the searchStrs in str, -1 if no match
    Since:
    
    3.0 Changed signature from indexOfAny(String, String[]) to indexOfAny(CharSequence, CharSequence...)
  - lastIndexOfAny
```
public static int lastIndexOfAny(CharSequence str,
                 CharSequence... searchStrs)
```
    Find the latest index of any of a set of potential substrings.
    
    A null CharSequence will return -1. A null search array will return -1. A null or zero length search array entry will be ignored, but a search array containing "" will return the length of str if str is not null. This method uses String.indexOf(String) if possible
```
 StringUtils.lastIndexOfAny(null, *)                   = -1
 StringUtils.lastIndexOfAny(*, null)                   = -1
 StringUtils.lastIndexOfAny(*, [])                     = -1
 StringUtils.lastIndexOfAny(*, [null])                 = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["ab","cd"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["cd","ab"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn",""])   = 10
 
```
    Parameters:
    str - the CharSequence to check, may be null
    searchStrs - the CharSequences to search for, may be null
    
    Returns:
    the last index of any of the CharSequences, -1 if no match
    Since:
    
    3.0 Changed signature from lastIndexOfAny(String, String[]) to lastIndexOfAny(CharSequence, CharSequence)
  - substring
```
public static String substring(String str,
               int start)
```
    Gets a substring from the specified String avoiding exceptions.
    
    A negative start position can be used to start n characters from the end of the String.
    
    A null String will return null. An empty ("") String will return "".
```
 StringUtils.substring(null, *)   = null
 StringUtils.substring("", *)     = ""
 StringUtils.substring("abc", 0)  = "abc"
 StringUtils.substring("abc", 2)  = "c"
 StringUtils.substring("abc", 4)  = ""
 StringUtils.substring("abc", -2) = "bc"
 StringUtils.substring("abc", -4) = "abc"
 
```
    Parameters:
    str - the String to get the substring from, may be null
    start - the position to start from, negative means count back from the end of the String by this many characters
    
    Returns:
    substring from start position, null if null String input
  - substring
```
public static String substring(String str,
               int start,
               int end)
```
    Gets a substring from the specified String avoiding exceptions.
    
    A negative start position can be used to start/end n characters from the end of the String.
    
    The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.
    
    If start is not strictly to the left of end, "" is returned.
```
 StringUtils.substring(null, *, *)    = null
 StringUtils.substring("", * ,  *)    = "";
 StringUtils.substring("abc", 0, 2)   = "ab"
 StringUtils.substring("abc", 2, 0)   = ""
 StringUtils.substring("abc", 2, 4)   = "c"
 StringUtils.substring("abc", 4, 6)   = ""
 StringUtils.substring("abc", 2, 2)   = ""
 StringUtils.substring("abc", -2, -1) = "b"
 StringUtils.substring("abc", -4, 2)  = "ab"
 
```
    Parameters:
    str - the String to get the substring from, may be null
    start - the position to start from, negative means count back from the end of the String by this many characters
    end - the position to end at (exclusive), negative means count back from the end of the String by this many characters
    
    Returns:
    substring from start position to end position, null if null String input
  - left
```
public static String left(String str,
          int len)
```
    Gets the leftmost len characters of a String.
    
    If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.
```
 StringUtils.left(null, *)    = null
 StringUtils.left(*, -ve)     = ""
 StringUtils.left("", *)      = ""
 StringUtils.left("abc", 0)   = ""
 StringUtils.left("abc", 2)   = "ab"
 StringUtils.left("abc", 4)   = "abc"
 
```
    Parameters:
    str - the String to get the leftmost characters from, may be null
    len - the length of the required String
    
    Returns:
    the leftmost characters, null if null String input
  - right
```
public static String right(String str,
           int len)
```
    Gets the rightmost len characters of a String.
    
    If len characters are not available, or the String is null, the String will be returned without an an exception. An empty String is returned if len is negative.
```
 StringUtils.right(null, *)    = null
 StringUtils.right(*, -ve)     = ""
 StringUtils.right("", *)      = ""
 StringUtils.right("abc", 0)   = ""
 StringUtils.right("abc", 2)   = "bc"
 StringUtils.right("abc", 4)   = "abc"
 
```
    Parameters:
    str - the String to get the rightmost characters from, may be null
    len - the length of the required String
    
    Returns:
    the rightmost characters, null if null String input
  - mid
```
public static String mid(String str,
         int pos,
         int len)
```
    Gets len characters from the middle of a String.
    
    If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An empty String is returned if len is negative or exceeds the length of str.
```
 StringUtils.mid(null, *, *)    = null
 StringUtils.mid(*, *, -ve)     = ""
 StringUtils.mid("", 0, *)      = ""
 StringUtils.mid("abc", 0, 2)   = "ab"
 StringUtils.mid("abc", 0, 4)   = "abc"
 StringUtils.mid("abc", 2, 4)   = "c"
 StringUtils.mid("abc", 4, 2)   = ""
 StringUtils.mid("abc", -2, 2)  = "ab"
 
```
    Parameters:
    str - the String to get the characters from, may be null
    pos - the position to start from, negative treated as zero
    len - the length of the required String
    
    Returns:
    the middle characters, null if null String input
  - substringBefore
```
public static String substringBefore(String str,
                     String separator)
```
    Gets the substring before the first occurrence of a separator. The separator is not returned.
    
    A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the input string.
    
    If nothing is found, the string input is returned.
```
 StringUtils.substringBefore(null, *)      = null
 StringUtils.substringBefore("", *)        = ""
 StringUtils.substringBefore("abc", "a")   = ""
 StringUtils.substringBefore("abcba", "b") = "a"
 StringUtils.substringBefore("abc", "c")   = "ab"
 StringUtils.substringBefore("abc", "d")   = "abc"
 StringUtils.substringBefore("abc", "")    = ""
 StringUtils.substringBefore("abc", null)  = "abc"
 
```
    Parameters:
    str - the String to get a substring from, may be null
    separator - the String to search for, may be null
    
    Returns:
    the substring before the first occurrence of the separator, null if null String input
    Since:
    
    2.0
  - substringAfter
```
public static String substringAfter(String str,
                    String separator)
```
    Gets the substring after the first occurrence of a separator. The separator is not returned.
    
    A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.
    
    If nothing is found, the empty string is returned.
```
 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter(*, null)      = ""
 StringUtils.substringAfter("abc", "a")   = "bc"
 StringUtils.substringAfter("abcba", "b") = "cba"
 StringUtils.substringAfter("abc", "c")   = ""
 StringUtils.substringAfter("abc", "d")   = ""
 StringUtils.substringAfter("abc", "")    = "abc"
 
```
    Parameters:
    str - the String to get a substring from, may be null
    separator - the String to search for, may be null
    
    Returns:
    the substring after the first occurrence of the separator, null if null String input
    Since:
    
    2.0
  - substringBeforeLast
```
public static String substringBeforeLast(String str,
                         String separator)
```
    Gets the substring before the last occurrence of a separator. The separator is not returned.
    
    A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the input string.
    
    If nothing is found, the string input is returned.
```
 StringUtils.substringBeforeLast(null, *)      = null
 StringUtils.substringBeforeLast("", *)        = ""
 StringUtils.substringBeforeLast("abcba", "b") = "abc"
 StringUtils.substringBeforeLast("abc", "c")   = "ab"
 StringUtils.substringBeforeLast("a", "a")     = ""
 StringUtils.substringBeforeLast("a", "z")     = "a"
 StringUtils.substringBeforeLast("a", null)    = "a"
 StringUtils.substringBeforeLast("a", "")      = "a"
 
```
    Parameters:
    str - the String to get a substring from, may be null
    separator - the String to search for, may be null
    
    Returns:
    the substring before the last occurrence of the separator, null if null String input
    Since:
    
    2.0
  - substringAfterLast
```
public static String substringAfterLast(String str,
                        String separator)
```
    Gets the substring after the last occurrence of a separator. The separator is not returned.
    
    A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the empty string if the input string is not null.
    
    If nothing is found, the empty string is returned.
```
 StringUtils.substringAfterLast(null, *)      = null
 StringUtils.substringAfterLast("", *)        = ""
 StringUtils.substringAfterLast(*, "")        = ""
 StringUtils.substringAfterLast(*, null)      = ""
 StringUtils.substringAfterLast("abc", "a")   = "bc"
 StringUtils.substringAfterLast("abcba", "b") = "a"
 StringUtils.substringAfterLast("abc", "c")   = ""
 StringUtils.substringAfterLast("a", "a")     = ""
 StringUtils.substringAfterLast("a", "z")     = ""
 
```
    Parameters:
    str - the String to get a substring from, may be null
    separator - the String to search for, may be null
    
    Returns:
    the substring after the last occurrence of the separator, null if null String input
    Since:
    
    2.0
  - substringBetween
```
public static String substringBetween(String str,
                      String tag)
```
    Gets the String that is nested in between two instances of the same String.
    
    A null input String returns null. A null tag returns null.
```
 StringUtils.substringBetween(null, *)            = null
 StringUtils.substringBetween("", "")             = ""
 StringUtils.substringBetween("", "tag")          = null
 StringUtils.substringBetween("tagabctag", null)  = null
 StringUtils.substringBetween("tagabctag", "")    = ""
 StringUtils.substringBetween("tagabctag", "tag") = "abc"
 
```
    Parameters:
    str - the String containing the substring, may be null
    tag - the String before and after the substring, may be null
    
    Returns:
    the substring, null if no match
    Since:
    
    2.0
  - substringBetween
```
public static String substringBetween(String str,
                      String open,
                      String close)
```
    Gets the String that is nested in between two Strings. Only the first match is returned.
    
    A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.
```
 StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
 StringUtils.substringBetween(null, *, *)          = null
 StringUtils.substringBetween(*, null, *)          = null
 StringUtils.substringBetween(*, *, null)          = null
 StringUtils.substringBetween("", "", "")          = ""
 StringUtils.substringBetween("", "", "]")         = null
 StringUtils.substringBetween("", "[", "]")        = null
 StringUtils.substringBetween("yabcz", "", "")     = ""
 StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
 StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"
 
```
    Parameters:
    str - the String containing the substring, may be null
    open - the String before the substring, may be null
    close - the String after the substring, may be null
    
    Returns:
    the substring, null if no match
    Since:
    
    2.0
  - substringsBetween
```
public static String[] substringsBetween(String str,
                         String open,
                         String close)
```
    Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.
    
    A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns null (no match).
```
 StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
 StringUtils.substringsBetween(null, *, *)            = null
 StringUtils.substringsBetween(*, null, *)            = null
 StringUtils.substringsBetween(*, *, null)            = null
 StringUtils.substringsBetween("", "[", "]")          = []
 
```
    Parameters:
    str - the String containing the substrings, null returns null, empty returns empty
    open - the String identifying the start of the substring, empty returns null
    close - the String identifying the end of the substring, empty returns null
    
    Returns:
    a String Array of substrings, or null if no match
    Since:
    
    2.3
  - split
```
public static String[] split(String str)
```
    Splits the provided text into an array, using whitespace as the separator. Whitespace is defined by Character.isWhitespace(char).
    
    The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.
    
    A null input String returns null.
```
 StringUtils.split(null)       = null
 StringUtils.split("")         = []
 StringUtils.split("abc def")  = ["abc", "def"]
 StringUtils.split("abc  def") = ["abc", "def"]
 StringUtils.split(" abc ")    = ["abc"]
 
```
    Parameters:
    str - the String to parse, may be null
    
    Returns:
    an array of parsed Strings, null if null String input
  - split
```
public static String[] split(String str,
             char separatorChar)
```
    Splits the provided text into an array, separator specified. This is an alternative to using StringTokenizer.
    
    The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.
    
    A null input String returns null.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
 StringUtils.split("a:b:c", '.')    = ["a:b:c"]
 StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChar - the character used as the delimiter
    
    Returns:
    an array of parsed Strings, null if null String input
    Since:
    
    2.0
  - split
```
public static String[] split(String str,
             String separatorChars)
```
    Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.
    
    The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.
    
    A null input String returns null. A null separatorChars splits on whitespace.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("abc def", null) = ["abc", "def"]
 StringUtils.split("abc def", " ")  = ["abc", "def"]
 StringUtils.split("abc  def", " ") = ["abc", "def"]
 StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChars - the characters used as the delimiters, null splits on whitespace
    
    Returns:
    an array of parsed Strings, null if null String input
  - split
```
public static String[] split(String str,
             String separatorChars,
             int max)
```
    Splits the provided text into an array with a maximum length, separators specified.
    
    The separator is not included in the returned String array. Adjacent separators are treated as one separator.
    
    A null input String returns null. A null separatorChars splits on whitespace.
    
    If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).
```
 StringUtils.split(null, *, *)            = null
 StringUtils.split("", *, *)              = []
 StringUtils.split("ab cd ef", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.split("ab   cd ef", null, 0) = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChars - the characters used as the delimiters, null splits on whitespace
    max - the maximum number of elements to include in the array. A zero or negative value implies no limit
    
    Returns:
    an array of parsed Strings, null if null String input
  - splitByWholeSeparator
```
public static String[] splitByWholeSeparator(String str,
                             String separator)
```
    Splits the provided text into an array, separator string specified.
    
    The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.
    
    A null input String returns null. A null separator splits on whitespace.
```
 StringUtils.splitByWholeSeparator(null, *)               = null
 StringUtils.splitByWholeSeparator("", *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separator - String containing the String to be used as a delimiter, null splits on whitespace
    
    Returns:
    an array of parsed Strings, null if null String was input
  - splitByWholeSeparator
```
public static String[] splitByWholeSeparator(String str,
                             String separator,
                             int max)
```
    Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.
    
    The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.
    
    A null input String returns null. A null separator splits on whitespace.
```
 StringUtils.splitByWholeSeparator(null, *, *)               = null
 StringUtils.splitByWholeSeparator("", *, *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separator - String containing the String to be used as a delimiter, null splits on whitespace
    max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
    
    Returns:
    an array of parsed Strings, null if null String was input
  - splitByWholeSeparatorPreserveAllTokens
```
public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                              String separator)
```
    Splits the provided text into an array, separator string specified.
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.
    
    A null input String returns null. A null separator splits on whitespace.
```
 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separator - String containing the String to be used as a delimiter, null splits on whitespace
    
    Returns:
    an array of parsed Strings, null if null String was input
    Since:
    
    2.4
  - splitByWholeSeparatorPreserveAllTokens
```
public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                              String separator,
                                              int max)
```
    Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.
    
    A null input String returns null. A null separator splits on whitespace.
```
 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]
 
```
    Parameters:
    str - the String to parse, may be null
    separator - String containing the String to be used as a delimiter, null splits on whitespace
    max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
    
    Returns:
    an array of parsed Strings, null if null String was input
    Since:
    
    2.4
  - splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str)
```
    Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer. Whitespace is defined by Character.isWhitespace(char).
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.
    
    A null input String returns null.
```
 StringUtils.splitPreserveAllTokens(null)       = null
 StringUtils.splitPreserveAllTokens("")         = []
 StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
 StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]
 
```
    Parameters:
    str - the String to parse, may be null
    
    Returns:
    an array of parsed Strings, null if null String input
    Since:
    
    2.1
  - splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str,
                              char separatorChar)
```
    Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.
    
    A null input String returns null.
```
 StringUtils.splitPreserveAllTokens(null, *)         = null
 StringUtils.splitPreserveAllTokens("", *)           = []
 StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
 StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
 StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
 StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
 StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
 StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
 StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChar - the character used as the delimiter, null splits on whitespace
    
    Returns:
    an array of parsed Strings, null if null String input
    Since:
    
    2.1
  - splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str,
                              String separatorChars)
```
    Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.
    
    A null input String returns null. A null separatorChars splits on whitespace.
```
 StringUtils.splitPreserveAllTokens(null, *)           = null
 StringUtils.splitPreserveAllTokens("", *)             = []
 StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
 StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
 StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
 StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChars - the characters used as the delimiters, null splits on whitespace
    
    Returns:
    an array of parsed Strings, null if null String input
    Since:
    
    2.1
  - splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str,
                              String separatorChars,
                              int max)
```
    Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
    
    The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. Adjacent separators are treated as one separator.
    
    A null input String returns null. A null separatorChars splits on whitespace.
    
    If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).
```
 StringUtils.splitPreserveAllTokens(null, *, *)            = null
 StringUtils.splitPreserveAllTokens("", *, *)              = []
 StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]
 
```
    Parameters:
    str - the String to parse, may be null
    separatorChars - the characters used as the delimiters, null splits on whitespace
    max - the maximum number of elements to include in the array. A zero or negative value implies no limit
    
    Returns:
    an array of parsed Strings, null if null String input
    Since:
    
    2.1
  - join
```
public static <T> String join(T... elements)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No separator is added to the joined String. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null)            = null
 StringUtils.join([])              = ""
 StringUtils.join([null])          = ""
 StringUtils.join(["a", "b", "c"]) = "abc"
 StringUtils.join([null, "", "a"]) = "a"
 
```
    Type Parameters:
    T - the specific type of values to join together
    Parameters:
    elements - the values to join together, may be null
    
    Returns:
    the joined String, null if null array input
    Since:
    
    2.0, 3.0 Changed signature to use varargs
  - join
```
public static String join(Object[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    2.0
  - join
```
public static String join(long[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(int[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(short[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(byte[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(char[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(float[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(double[] array,
          char separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(Object[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    2.0
  - join
```
public static String join(long[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(int[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(byte[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(short[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(char[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(double[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(float[] array,
          char separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join([1, 2, 3], ';')  = "1;2;3"
 StringUtils.join([1, 2, 3], null) = "123"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use
    startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
    endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
    
    Returns:
    the joined String, null if null array input
    Since:
    
    3.2
  - join
```
public static String join(Object[] array,
          String separator)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use, null treated as ""
    
    Returns:
    the joined String, null if null array input
  - join
```
public static String join(Object[] array,
          String separator,
          int startIndex,
          int endIndex)
```
    Joins the elements of the provided array into a single String containing the provided list of elements.
    
    No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *, *, *)                = null
 StringUtils.join([], *, *, *)                  = ""
 StringUtils.join([null], *, *, *)              = ""
 StringUtils.join(["a", "b", "c"], "--", 0, 3)  = "a--b--c"
 StringUtils.join(["a", "b", "c"], "--", 1, 3)  = "b--c"
 StringUtils.join(["a", "b", "c"], "--", 2, 3)  = "c"
 StringUtils.join(["a", "b", "c"], "--", 2, 2)  = ""
 StringUtils.join(["a", "b", "c"], null, 0, 3)  = "abc"
 StringUtils.join(["a", "b", "c"], "", 0, 3)    = "abc"
 StringUtils.join([null, "", "a"], ',', 0, 3)   = ",,a"
 
```
    Parameters:
    array - the array of values to join together, may be null
    separator - the separator character to use, null treated as ""
    startIndex - the first index to start joining from.
    endIndex - the index to stop joining from (exclusive).
    
    Returns:
    the joined String, null if null array input; or the empty string if endIndex - startIndex <= 0. The number of joined entries is given by endIndex - startIndex
    
    Throws:
    
    ArrayIndexOutOfBoundsException - ife
    startIndex < 0 or
    startIndex >= array.length() or
    endIndex < 0 or
    endIndex > array.length()
  - join
```
public static String join(Iterator<?> iterator,
          char separator)
```
    Joins the elements of the provided Iterator into a single String containing the provided elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.
    
    See the examples here: join(Object[],char).
    
    Parameters:
    iterator - the Iterator of values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null iterator input
    Since:
    
    2.0
  - join
```
public static String join(Iterator<?> iterator,
          String separator)
```
    Joins the elements of the provided Iterator into a single String containing the provided elements.
    
    No delimiter is added before or after the list. A null separator is the same as an empty String ("").
    
    See the examples here: join(Object[],String).
    
    Parameters:
    iterator - the Iterator of values to join together, may be null
    separator - the separator character to use, null treated as ""
    
    Returns:
    the joined String, null if null iterator input
  - join
```
public static String join(Iterable<?> iterable,
          char separator)
```
    Joins the elements of the provided Iterable into a single String containing the provided elements.
    
    No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.
    
    See the examples here: join(Object[],char).
    
    Parameters:
    iterable - the Iterable providing the values to join together, may be null
    separator - the separator character to use
    
    Returns:
    the joined String, null if null iterator input
    Since:
    
    2.3
  - join
```
public static String join(Iterable<?> iterable,
          String separator)
```
    Joins the elements of the provided Iterable into a single String containing the provided elements.
    
    No delimiter is added before or after the list. A null separator is the same as an empty String ("").
    
    See the examples here: join(Object[],String).
    
    Parameters:
    iterable - the Iterable providing the values to join together, may be null
    separator - the separator character to use, null treated as ""
    
    Returns:
    the joined String, null if null iterator input
    Since:
    
    2.3
  - deleteWhitespace
```
public static String deleteWhitespace(String str)
```
    Deletes all whitespaces from a String as defined by Character.isWhitespace(char).
```
 StringUtils.deleteWhitespace(null)         = null
 StringUtils.deleteWhitespace("")           = ""
 StringUtils.deleteWhitespace("abc")        = "abc"
 StringUtils.deleteWhitespace("   ab  c  ") = "abc"
 
```
    Parameters:
    str - the String to delete whitespace from, may be null
    
    Returns:
    the String without whitespaces, null if null String input
  - removeStart
```
public static String removeStart(String str,
                 String remove)
```
    Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.
```
 StringUtils.removeStart(null, *)      = null
 StringUtils.removeStart("", *)        = ""
 StringUtils.removeStart(*, null)      = *
 StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStart("domain.com", "www.")       = "domain.com"
 StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStart("abc", "")    = "abc"
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the String to search for and remove, may be null
    
    Returns:
    the substring with the string removed if found, null if null String input
    Since:
    
    2.1
  - removeStartIgnoreCase
```
public static String removeStartIgnoreCase(String str,
                           String remove)
```
    Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.
```
 StringUtils.removeStartIgnoreCase(null, *)      = null
 StringUtils.removeStartIgnoreCase("", *)        = ""
 StringUtils.removeStartIgnoreCase(*, null)      = *
 StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStartIgnoreCase("abc", "")    = "abc"
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the String to search for (case insensitive) and remove, may be null
    
    Returns:
    the substring with the string removed if found, null if null String input
    Since:
    
    2.4
  - removeEnd
```
public static String removeEnd(String str,
               String remove)
```
    Removes a substring only if it is at the end of a source string, otherwise returns the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.
```
 StringUtils.removeEnd(null, *)      = null
 StringUtils.removeEnd("", *)        = ""
 StringUtils.removeEnd(*, null)      = *
 StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEnd("abc", "")    = "abc"
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the String to search for and remove, may be null
    
    Returns:
    the substring with the string removed if found, null if null String input
    Since:
    
    2.1
  - removeEndIgnoreCase
```
public static String removeEndIgnoreCase(String str,
                         String remove)
```
    Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.
```
 StringUtils.removeEndIgnoreCase(null, *)      = null
 StringUtils.removeEndIgnoreCase("", *)        = ""
 StringUtils.removeEndIgnoreCase(*, null)      = *
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
 StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the String to search for (case insensitive) and remove, may be null
    
    Returns:
    the substring with the string removed if found, null if null String input
    Since:
    
    2.4
  - remove
```
public static String remove(String str,
            String remove)
```
    Removes all occurrences of a substring from within the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.
```
 StringUtils.remove(null, *)        = null
 StringUtils.remove("", *)          = ""
 StringUtils.remove(*, null)        = *
 StringUtils.remove(*, "")          = *
 StringUtils.remove("queued", "ue") = "qd"
 StringUtils.remove("queued", "zz") = "queued"
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the String to search for and remove, may be null
    
    Returns:
    the substring with the string removed if found, null if null String input
    Since:
    
    2.1
  - remove
```
public static String remove(String str,
            char remove)
```
    Removes all occurrences of a character from within the source string.
    
    A null source string will return null. An empty ("") source string will return the empty string.
```
 StringUtils.remove(null, *)       = null
 StringUtils.remove("", *)         = ""
 StringUtils.remove("queued", 'u') = "qeed"
 StringUtils.remove("queued", 'z') = "queued"
 
```
    Parameters:
    str - the source String to search, may be null
    remove - the char to search for and remove, may be null
    
    Returns:
    the substring with the char removed if found, null if null String input
    Since:
    
    2.1
  - replaceOnce
```
public static String replaceOnce(String text,
                 String searchString,
                 String replacement)
```
    Replaces a String with another String inside a larger String, once.
    
    A null reference passed to this method is a no-op.
```
 StringUtils.replaceOnce(null, *, *)        = null
 StringUtils.replaceOnce("", *, *)          = ""
 StringUtils.replaceOnce("any", null, *)    = "any"
 StringUtils.replaceOnce("any", *, null)    = "any"
 StringUtils.replaceOnce("any", "", *)      = "any"
 StringUtils.replaceOnce("aba", "a", null)  = "aba"
 StringUtils.replaceOnce("aba", "a", "")    = "ba"
 StringUtils.replaceOnce("aba", "a", "z")   = "zba"
 
```
    Parameters:
    text - text to search and replace in, may be null
    searchString - the String to search for, may be null
    replacement - the String to replace with, may be null
    
    Returns:
    the text with any replacements processed, null if null String input
    See Also:
    replace(String text, String searchString, String replacement, int max)
  - replace
```
public static String replace(String text,
             String searchString,
             String replacement)
```
    Replaces all occurrences of a String within another String.
    
    A null reference passed to this method is a no-op.
```
 StringUtils.replace(null, *, *)        = null
 StringUtils.replace("", *, *)          = ""
 StringUtils.replace("any", null, *)    = "any"
 StringUtils.replace("any", *, null)    = "any"
 StringUtils.replace("any", "", *)      = "any"
 StringUtils.replace("aba", "a", null)  = "aba"
 StringUtils.replace("aba", "a", "")    = "b"
 StringUtils.replace("aba", "a", "z")   = "zbz"
 
```
    Parameters:
    text - text to search and replace in, may be null
    searchString - the String to search for, may be null
    replacement - the String to replace it with, may be null
    
    Returns:
    the text with any replacements processed, null if null String input
    See Also:
    replace(String text, String searchString, String replacement, int max)
  - replace
```
public static String replace(String text,
             String searchString,
             String replacement,
             int max)
```
    Replaces a String with another String inside a larger String, for the first max values of the search String.
    
    A null reference passed to this method is a no-op.
```
 StringUtils.replace(null, *, *, *)         = null
 StringUtils.replace("", *, *, *)           = ""
 StringUtils.replace("any", null, *, *)     = "any"
 StringUtils.replace("any", *, null, *)     = "any"
 StringUtils.replace("any", "", *, *)       = "any"
 StringUtils.replace("any", *, *, 0)        = "any"
 StringUtils.replace("abaa", "a", null, -1) = "abaa"
 StringUtils.replace("abaa", "a", "", -1)   = "b"
 StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
 StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
 StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"
 
```
    Parameters:
    text - text to search and replace in, may be null
    searchString - the String to search for, may be null
    replacement - the String to replace it with, may be null
    max - maximum number of values to replace, or -1 if no maximum
    
    Returns:
    the text with any replacements processed, null if null String input
  - replaceEach
```
public static String replaceEach(String text,
                 String[] searchList,
                 String[] replacementList)
```
    Replaces all occurrences of Strings within another String.
    
    A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.
```
  StringUtils.replaceEach(null, *, *)        = null
  StringUtils.replaceEach("", *, *)          = ""
  StringUtils.replaceEach("aba", null, null) = "aba"
  StringUtils.replaceEach("aba", new String[0], null) = "aba"
  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
  (example of how it does not repeat)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"
 
```
    Parameters:
    text - text to search and replace in, no-op if null
    searchList - the Strings to search for, no-op if null
    replacementList - the Strings to replace them with, no-op if null
    
    Returns:
    the text with any replacements processed, null if null String input
    
    Throws:
    
    IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
    Since:
    
    2.4
  - replaceEachRepeatedly
```
public static String replaceEachRepeatedly(String text,
                           String[] searchList,
                           String[] replacementList)
```
    Replaces all occurrences of Strings within another String.
    
    A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored.
```
  StringUtils.replaceEach(null, *, *, *) = null
  StringUtils.replaceEach("", *, *, *) = ""
  StringUtils.replaceEach("aba", null, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[0], null, *) = "aba"
  StringUtils.replaceEach("aba", null, new String[0], *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte"
  (example of how it repeats)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, true) = IllegalStateException
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, false) = "dcabe"
 
```
    Parameters:
    text - text to search and replace in, no-op if null
    searchList - the Strings to search for, no-op if null
    replacementList - the Strings to replace them with, no-op if null
    
    Returns:
    the text with any replacements processed, null if null String input
    
    Throws:
    
    IllegalStateException - if the search is repeating and there is an endless loop due to outputs of one being inputs to another
    
    IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
    Since:
    
    2.4
  - replaceChars
```
public static String replaceChars(String str,
                  char searchChar,
                  char replaceChar)
```
    Replaces all occurrences of a character in a String with another. This is a null-safe version of String.replace(char, char).
    
    A null string input returns null. An empty ("") string input returns an empty string.
```
 StringUtils.replaceChars(null, *, *)        = null
 StringUtils.replaceChars("", *, *)          = ""
 StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
 StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
 
```
    Parameters:
    str - String to replace characters in, may be null
    searchChar - the character to search for, may be null
    replaceChar - the character to replace, may be null
    
    Returns:
    modified String, null if null string input
    Since:
    
    2.0
  - replaceChars
```
public static String replaceChars(String str,
                  String searchChars,
                  String replaceChars)
```
    Replaces multiple characters in a String in one go. This method can also be used to delete characters.
    
    For example:
    replaceChars("hello", "ho", "jy") = jelly.
    
    A null string input returns null. An empty ("") string input returns an empty string. A null or empty set of search characters returns the input string.
    
    The length of the search characters should normally equal the length of the replace characters. If the search characters is longer, then the extra search characters are deleted. If the search characters is shorter, then the extra replace characters are ignored.
```
 StringUtils.replaceChars(null, *, *)           = null
 StringUtils.replaceChars("", *, *)             = ""
 StringUtils.replaceChars("abc", null, *)       = "abc"
 StringUtils.replaceChars("abc", "", *)         = "abc"
 StringUtils.replaceChars("abc", "b", null)     = "ac"
 StringUtils.replaceChars("abc", "b", "")       = "ac"
 StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
 StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
 StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
 
```
    Parameters:
    str - String to replace characters in, may be null
    searchChars - a set of characters to search for, may be null
    replaceChars - a set of characters to replace, may be null
    
    Returns:
    modified String, null if null string input
    Since:
    
    2.0
  - overlay
```
public static String overlay(String str,
             String overlay,
             int start,
             int end)
```
    Overlays part of a String with another String.
    
    A null string input returns null. A negative index is treated as zero. An index greater than the string length is treated as the string length. The start index is always the smaller of the two indices.
```
 StringUtils.overlay(null, *, *, *)            = null
 StringUtils.overlay("", "abc", 0, 0)          = "abc"
 StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
 StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
 StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
 StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
 StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
 StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
 StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"
 
```
    Parameters:
    str - the String to do overlaying in, may be null
    overlay - the String to overlay, may be null
    start - the position to start overlaying at
    end - the position to stop overlaying before
    
    Returns:
    overlayed String, null if null String input
    Since:
    
    2.0
  - chomp
```
public static String chomp(String str)
```
    Removes one newline from end of a String if it's there, otherwise leave it alone. A newline is "\n", "\r", or "\r\n".
    
    NOTE: This method changed in 2.0. It now more closely matches Perl chomp.
```
 StringUtils.chomp(null)          = null
 StringUtils.chomp("")            = ""
 StringUtils.chomp("abc \r")      = "abc "
 StringUtils.chomp("abc\n")       = "abc"
 StringUtils.chomp("abc\r\n")     = "abc"
 StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
 StringUtils.chomp("abc\n\r")     = "abc\n"
 StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
 StringUtils.chomp("\r")          = ""
 StringUtils.chomp("\n")          = ""
 StringUtils.chomp("\r\n")        = ""
 
```
    Parameters:
    str - the String to chomp a newline from, may be null
    
    Returns:
    String without newline, null if null String input
  - chop
```
public static String chop(String str)
```
    Remove the last character from a String.
    
    If the String ends in \r\n, then remove both of them.
```
 StringUtils.chop(null)          = null
 StringUtils.chop("")            = ""
 StringUtils.chop("abc \r")      = "abc "
 StringUtils.chop("abc\n")       = "abc"
 StringUtils.chop("abc\r\n")     = "abc"
 StringUtils.chop("abc")         = "ab"
 StringUtils.chop("abc\nabc")    = "abc\nab"
 StringUtils.chop("a")           = ""
 StringUtils.chop("\r")          = ""
 StringUtils.chop("\n")          = ""
 StringUtils.chop("\r\n")        = ""
 
```
    Parameters:
    str - the String to chop last character from, may be null
    
    Returns:
    String without last character, null if null String input
  - repeat
```
public static String repeat(String str,
            int repeat)
```
    Repeat a String repeat times to form a new String.
```
 StringUtils.repeat(null, 2) = null
 StringUtils.repeat("", 0)   = ""
 StringUtils.repeat("", 2)   = ""
 StringUtils.repeat("a", 3)  = "aaa"
 StringUtils.repeat("ab", 2) = "abab"
 StringUtils.repeat("a", -2) = ""
 
```
    Parameters:
    str - the String to repeat, may be null
    repeat - number of times to repeat str, negative treated as zero
    
    Returns:
    a new String consisting of the original String repeated, null if null String input
  - repeat
```
public static String repeat(String str,
            String separator,
            int repeat)
```
    Repeat a String repeat times to form a new String, with a String separator injected each time.
```
 StringUtils.repeat(null, null, 2) = null
 StringUtils.repeat(null, "x", 2)  = null
 StringUtils.repeat("", null, 0)   = ""
 StringUtils.repeat("", "", 2)     = ""
 StringUtils.repeat("", "x", 3)    = "xxx"
 StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"
 
```
    Parameters:
    str - the String to repeat, may be null
    separator - the String to inject, may be null
    repeat - number of times to repeat str, negative treated as zero
    
    Returns:
    a new String consisting of the original String repeated, null if null String input
    Since:
    
    2.5
  - repeat
```
public static String repeat(char ch,
            int repeat)
```
    Returns padding using the specified delimiter repeated to a given length.
```
 StringUtils.repeat('e', 0)  = ""
 StringUtils.repeat('e', 3)  = "eee"
 StringUtils.repeat('e', -2) = ""
 
```
    Note: this method doesn't not support padding with Unicode Supplementary Characters as they require a pair of chars to be represented. If you are needing to support full I18N of your applications consider using repeat(String, int) instead.
    Parameters:
    ch - character to repeat
    repeat - number of times to repeat char, negative treated as zero
    
    Returns:
    String with repeated character
    See Also:
    repeat(String, int)
  - rightPad
```
public static String rightPad(String str,
              int size)
```
    Right pad a String with spaces (' ').
    
    The String is padded to the size of size.
```
 StringUtils.rightPad(null, *)   = null
 StringUtils.rightPad("", 3)     = "   "
 StringUtils.rightPad("bat", 3)  = "bat"
 StringUtils.rightPad("bat", 5)  = "bat  "
 StringUtils.rightPad("bat", 1)  = "bat"
 StringUtils.rightPad("bat", -1) = "bat"
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    
    Returns:
    right padded String or original String if no padding is necessary, null if null String input
  - rightPad
```
public static String rightPad(String str,
              int size,
              char padChar)
```
    Right pad a String with a specified character.
    
    The String is padded to the size of size.
```
 StringUtils.rightPad(null, *, *)     = null
 StringUtils.rightPad("", 3, 'z')     = "zzz"
 StringUtils.rightPad("bat", 3, 'z')  = "bat"
 StringUtils.rightPad("bat", 5, 'z')  = "batzz"
 StringUtils.rightPad("bat", 1, 'z')  = "bat"
 StringUtils.rightPad("bat", -1, 'z') = "bat"
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    padChar - the character to pad with
    
    Returns:
    right padded String or original String if no padding is necessary, null if null String input
    Since:
    
    2.0
  - rightPad
```
public static String rightPad(String str,
              int size,
              String padStr)
```
    Right pad a String with a specified String.
    
    The String is padded to the size of size.
```
 StringUtils.rightPad(null, *, *)      = null
 StringUtils.rightPad("", 3, "z")      = "zzz"
 StringUtils.rightPad("bat", 3, "yz")  = "bat"
 StringUtils.rightPad("bat", 5, "yz")  = "batyz"
 StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
 StringUtils.rightPad("bat", 1, "yz")  = "bat"
 StringUtils.rightPad("bat", -1, "yz") = "bat"
 StringUtils.rightPad("bat", 5, null)  = "bat  "
 StringUtils.rightPad("bat", 5, "")    = "bat  "
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    padStr - the String to pad with, null or empty treated as single space
    
    Returns:
    right padded String or original String if no padding is necessary, null if null String input
  - leftPad
```
public static String leftPad(String str,
             int size)
```
    Left pad a String with spaces (' ').
    
    The String is padded to the size of size.
```
 StringUtils.leftPad(null, *)   = null
 StringUtils.leftPad("", 3)     = "   "
 StringUtils.leftPad("bat", 3)  = "bat"
 StringUtils.leftPad("bat", 5)  = "  bat"
 StringUtils.leftPad("bat", 1)  = "bat"
 StringUtils.leftPad("bat", -1) = "bat"
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    
    Returns:
    left padded String or original String if no padding is necessary, null if null String input
  - leftPad
```
public static String leftPad(String str,
             int size,
             char padChar)
```
    Left pad a String with a specified character.
    
    Pad to a size of size.
```
 StringUtils.leftPad(null, *, *)     = null
 StringUtils.leftPad("", 3, 'z')     = "zzz"
 StringUtils.leftPad("bat", 3, 'z')  = "bat"
 StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
 StringUtils.leftPad("bat", 1, 'z')  = "bat"
 StringUtils.leftPad("bat", -1, 'z') = "bat"
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    padChar - the character to pad with
    
    Returns:
    left padded String or original String if no padding is necessary, null if null String input
    Since:
    
    2.0
  - leftPad
```
public static String leftPad(String str,
             int size,
             String padStr)
```
    Left pad a String with a specified String.
    
    Pad to a size of size.
```
 StringUtils.leftPad(null, *, *)      = null
 StringUtils.leftPad("", 3, "z")      = "zzz"
 StringUtils.leftPad("bat", 3, "yz")  = "bat"
 StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
 StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
 StringUtils.leftPad("bat", 1, "yz")  = "bat"
 StringUtils.leftPad("bat", -1, "yz") = "bat"
 StringUtils.leftPad("bat", 5, null)  = "  bat"
 StringUtils.leftPad("bat", 5, "")    = "  bat"
 
```
    Parameters:
    str - the String to pad out, may be null
    size - the size to pad to
    padStr - the String to pad with, null or empty treated as single space
    
    Returns:
    left padded String or original String if no padding is necessary, null if null String input
  - length
```
public static int length(CharSequence cs)
```
    Gets a CharSequence length or 0 if the CharSequence is null.
    
    Parameters:
    cs - a CharSequence or null
    
    Returns:
    CharSequence length or 0 if the CharSequence is null.
    Since:
    
    2.4, 3.0 Changed signature from length(String) to length(CharSequence)
  - center
```
public static String center(String str,
            int size)
```
    Centers a String in a larger String of size size using the space character (' ').
    
    If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.
    
    Equivalent to center(str, size, " ").
```
 StringUtils.center(null, *)   = null
 StringUtils.center("", 4)     = "    "
 StringUtils.center("ab", -1)  = "ab"
 StringUtils.center("ab", 4)   = " ab "
 StringUtils.center("abcd", 2) = "abcd"
 StringUtils.center("a", 4)    = " a  "
 
```
    Parameters:
    str - the String to center, may be null
    size - the int size of new String, negative treated as zero
    
    Returns:
    centered String, null if null String input
  - center
```
public static String center(String str,
            int size,
            char padChar)
```
    Centers a String in a larger String of size size. Uses a supplied character as the value to pad the String with.
    
    If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.
```
 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, ' ')     = "    "
 StringUtils.center("ab", -1, ' ')  = "ab"
 StringUtils.center("ab", 4, ' ')   = " ab "
 StringUtils.center("abcd", 2, ' ') = "abcd"
 StringUtils.center("a", 4, ' ')    = " a  "
 StringUtils.center("a", 4, 'y')    = "yayy"
 
```
    Parameters:
    str - the String to center, may be null
    size - the int size of new String, negative treated as zero
    padChar - the character to pad the new String with
    
    Returns:
    centered String, null if null String input
    Since:
    
    2.0
  - center
```
public static String center(String str,
            int size,
            String padStr)
```
    Centers a String in a larger String of size size. Uses a supplied String as the value to pad the String with.
    
    If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.
```
 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, " ")     = "    "
 StringUtils.center("ab", -1, " ")  = "ab"
 StringUtils.center("ab", 4, " ")   = " ab "
 StringUtils.center("abcd", 2, " ") = "abcd"
 StringUtils.center("a", 4, " ")    = " a  "
 StringUtils.center("a", 4, "yz")   = "yayz"
 StringUtils.center("abc", 7, null) = "  abc  "
 StringUtils.center("abc", 7, "")   = "  abc  "
 
```
    Parameters:
    str - the String to center, may be null
    size - the int size of new String, negative treated as zero
    padStr - the String to pad the new String with, must not be null or empty
    
    Returns:
    centered String, null if null String input
    
    Throws:
    
    IllegalArgumentException - if padStr is null or empty
  - upperCase
```
public static String upperCase(String str)
```
    Converts a String to upper case as per String.toUpperCase().
    
    A null input String returns null.
```
 StringUtils.upperCase(null)  = null
 StringUtils.upperCase("")    = ""
 StringUtils.upperCase("aBc") = "ABC"
 
```
    Note: As described in the documentation for String.toUpperCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method #lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
    Parameters:
    str - the String to upper case, may be null
    
    Returns:
    the upper cased String, null if null String input
  - lowerCase
```
public static String lowerCase(String str)
```
    Converts a String to lower case as per String.toLowerCase().
    
    A null input String returns null.
```
 StringUtils.lowerCase(null)  = null
 StringUtils.lowerCase("")    = ""
 StringUtils.lowerCase("aBc") = "abc"
 
```
    Note: As described in the documentation for String.toLowerCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method #lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
    Parameters:
    str - the String to lower case, may be null
    
    Returns:
    the lower cased String, null if null String input
  - uncapitalize
```
public static String uncapitalize(String str)
```
    Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.
    
    For a word based algorithm, see org.apache.commons.lang3.text.WordUtils#uncapitalize(String). A null input String returns null.
```
 StringUtils.uncapitalize(null)  = null
 StringUtils.uncapitalize("")    = ""
 StringUtils.uncapitalize("Cat") = "cat"
 StringUtils.uncapitalize("CAT") = "cAT"
 
```
    Parameters:
    str - the String to uncapitalize, may be null
    
    Returns:
    the uncapitalized String, null if null String input
    Since:
    
    2.0
    
    See Also:
    #capitalize(String)
  - countMatches
```
public static int countMatches(CharSequence str,
               CharSequence sub)
```
    Counts how many times the substring appears in the larger string.
    
    A null or empty ("") String input returns 0.
```
 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", null)  = 0
 StringUtils.countMatches("abba", "")    = 0
 StringUtils.countMatches("abba", "a")   = 2
 StringUtils.countMatches("abba", "ab")  = 1
 StringUtils.countMatches("abba", "xxx") = 0
 
```
    Parameters:
    str - the CharSequence to check, may be null
    sub - the substring to count, may be null
    
    Returns:
    the number of occurrences, 0 if either CharSequence is null
    Since:
    
    3.0 Changed signature from countMatches(String, String) to countMatches(CharSequence, CharSequence)
  - countMatches
```
public static int countMatches(CharSequence str,
               char ch)
```
    Counts how many times the char appears in the given string.
    
    A null or empty ("") String input returns 0.
```
 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", 0)  = 0
 StringUtils.countMatches("abba", 'a')   = 2
 StringUtils.countMatches("abba", 'b')  = 2
 StringUtils.countMatches("abba", 'x') = 0
 
```
    Parameters:
    str - the CharSequence to check, may be null
    ch - the char to count
    
    Returns:
    the number of occurrences, 0 if the CharSequence is null
    Since:
    
    3.4
  - isAlpha
```
public static boolean isAlpha(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode letters.
    
    null will return false. An empty CharSequence (length()=0) will return false.
```
 StringUtils.isAlpha(null)   = false
 StringUtils.isAlpha("")     = false
 StringUtils.isAlpha("  ")   = false
 StringUtils.isAlpha("abc")  = true
 StringUtils.isAlpha("ab2c") = false
 StringUtils.isAlpha("ab-c") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains letters, and is non-null
    Since:
    
    3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence), 3.0 Changed "" to return false and not true
  - isAlphaSpace
```
public static boolean isAlphaSpace(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode letters and space (' ').
    
    null will return false An empty CharSequence (length()=0) will return true.
```
 StringUtils.isAlphaSpace(null)   = false
 StringUtils.isAlphaSpace("")     = true
 StringUtils.isAlphaSpace("  ")   = true
 StringUtils.isAlphaSpace("abc")  = true
 StringUtils.isAlphaSpace("ab c") = true
 StringUtils.isAlphaSpace("ab2c") = false
 StringUtils.isAlphaSpace("ab-c") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains letters and space, and is non-null
    Since:
    
    3.0 Changed signature from isAlphaSpace(String) to isAlphaSpace(CharSequence)
  - isAlphanumeric
```
public static boolean isAlphanumeric(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode letters or digits.
    
    null will return false. An empty CharSequence (length()=0) will return false.
```
 StringUtils.isAlphanumeric(null)   = false
 StringUtils.isAlphanumeric("")     = false
 StringUtils.isAlphanumeric("  ")   = false
 StringUtils.isAlphanumeric("abc")  = true
 StringUtils.isAlphanumeric("ab c") = false
 StringUtils.isAlphanumeric("ab2c") = true
 StringUtils.isAlphanumeric("ab-c") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains letters or digits, and is non-null
    Since:
    
    3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence), 3.0 Changed "" to return false and not true
  - isAlphanumericSpace
```
public static boolean isAlphanumericSpace(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode letters, digits or space (' ').
    
    null will return false. An empty CharSequence (length()=0) will return true.
```
 StringUtils.isAlphanumericSpace(null)   = false
 StringUtils.isAlphanumericSpace("")     = true
 StringUtils.isAlphanumericSpace("  ")   = true
 StringUtils.isAlphanumericSpace("abc")  = true
 StringUtils.isAlphanumericSpace("ab c") = true
 StringUtils.isAlphanumericSpace("ab2c") = true
 StringUtils.isAlphanumericSpace("ab-c") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains letters, digits or space, and is non-null
    Since:
    
    3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence)
  - isAsciiPrintable
```
public static boolean isAsciiPrintable(CharSequence cs)
```
    Checks if the CharSequence contains only ASCII printable characters.
    
    null will return false. An empty CharSequence (length()=0) will return true.
```
 StringUtils.isAsciiPrintable(null)     = false
 StringUtils.isAsciiPrintable("")       = true
 StringUtils.isAsciiPrintable(" ")      = true
 StringUtils.isAsciiPrintable("Ceki")   = true
 StringUtils.isAsciiPrintable("ab2c")   = true
 StringUtils.isAsciiPrintable("!ab-c~") = true
 StringUtils.isAsciiPrintable(" ") = true
 StringUtils.isAsciiPrintable("!") = true
 StringUtils.isAsciiPrintable("~") = true
 StringUtils.isAsciiPrintable("") = false
 StringUtils.isAsciiPrintable("Ceki Gülcü") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if every character is in the range 32 thru 126
    Since:
    
    2.1, 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)
  - isNumeric
```
public static boolean isNumeric(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode digits. A decimal point is not a Unicode digit and returns false.
    
    null will return false. An empty CharSequence (length()=0) will return false.
    
    Note that the method does not allow for a leading sign, either positive or negative. Also, if a String passes the numeric test, it may still generate a NumberFormatException when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range for int or long respectively.
```
 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = false
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("१२३")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false
 StringUtils.isNumeric("-123") = false
 StringUtils.isNumeric("+123") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains digits, and is non-null
    Since:
    
    3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence), 3.0 Changed "" to return false and not true
  - isNumericSpace
```
public static boolean isNumericSpace(CharSequence cs)
```
    Checks if the CharSequence contains only Unicode digits or space (' '). A decimal point is not a Unicode digit and returns false.
    
    null will return false. An empty CharSequence (length()=0) will return true.
```
 StringUtils.isNumericSpace(null)   = false
 StringUtils.isNumericSpace("")     = true
 StringUtils.isNumericSpace("  ")   = true
 StringUtils.isNumericSpace("123")  = true
 StringUtils.isNumericSpace("12 3") = true
 StringUtils.isNumeric("१२३")  = true
 StringUtils.isNumeric("१२ ३")  = true
 StringUtils.isNumericSpace("ab2c") = false
 StringUtils.isNumericSpace("12-3") = false
 StringUtils.isNumericSpace("12.3") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains digits or space, and is non-null
    Since:
    
    3.0 Changed signature from isNumericSpace(String) to isNumericSpace(CharSequence)
  - isWhitespace
```
public static boolean isWhitespace(CharSequence cs)
```
    Checks if the CharSequence contains only whitespace.
    
    null will return false. An empty CharSequence (length()=0) will return true.
```
 StringUtils.isWhitespace(null)   = false
 StringUtils.isWhitespace("")     = true
 StringUtils.isWhitespace("  ")   = true
 StringUtils.isWhitespace("abc")  = false
 StringUtils.isWhitespace("ab2c") = false
 StringUtils.isWhitespace("ab-c") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains whitespace, and is non-null
    Since:
    
    2.0, 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence)
  - isAllLowerCase
```
public static boolean isAllLowerCase(CharSequence cs)
```
    Checks if the CharSequence contains only lowercase characters.
    
    null will return false. An empty CharSequence (length()=0) will return false.
```
 StringUtils.isAllLowerCase(null)   = false
 StringUtils.isAllLowerCase("")     = false
 StringUtils.isAllLowerCase("  ")   = false
 StringUtils.isAllLowerCase("abc")  = true
 StringUtils.isAllLowerCase("abC") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains lowercase characters, and is non-null
    Since:
    
    2.5, 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)
  - isAllUpperCase
```
public static boolean isAllUpperCase(CharSequence cs)
```
    Checks if the CharSequence contains only uppercase characters.
    
    null will return false. An empty String (length()=0) will return false.
```
 StringUtils.isAllUpperCase(null)   = false
 StringUtils.isAllUpperCase("")     = false
 StringUtils.isAllUpperCase("  ")   = false
 StringUtils.isAllUpperCase("ABC")  = true
 StringUtils.isAllUpperCase("aBC") = false
 
```
    Parameters:
    cs - the CharSequence to check, may be null
    
    Returns:
    true if only contains uppercase characters, and is non-null
    Since:
    
    2.5, 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)
  - defaultString
```
public static String defaultString(String str)
```
    Returns either the passed in String, or if the String is null, an empty String ("").
```
 StringUtils.defaultString(null)  = ""
 StringUtils.defaultString("")    = ""
 StringUtils.defaultString("bat") = "bat"
 
```
    Parameters:
    str - the String to check, may be null
    
    Returns:
    the passed in String, or the empty String if it was null
    See Also:
    ObjectUtils.toString(Object), String.valueOf(Object)
  - defaultString
```
public static String defaultString(String str,
                   String defaultStr)
```
    Returns either the passed in String, or if the String is null, the value of defaultStr.
```
 StringUtils.defaultString(null, "NULL")  = "NULL"
 StringUtils.defaultString("", "NULL")    = ""
 StringUtils.defaultString("bat", "NULL") = "bat"
 
```
    Parameters:
    str - the String to check, may be null
    defaultStr - the default String to return if the input is null, may be null
    
    Returns:
    the passed in String, or the default if it was null
    See Also:
    ObjectUtils.toString(Object,String), String.valueOf(Object)
  - defaultIfBlank
```
public static <T extends CharSequence> T defaultIfBlank(T str,
                                        T defaultStr)
```
    Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.
```
 StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
 StringUtils.defaultIfBlank("", "NULL")    = "NULL"
 StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
 StringUtils.defaultIfBlank("bat", "NULL") = "bat"
 StringUtils.defaultIfBlank("", null)      = null
 
```
    Type Parameters:
    T - the specific kind of CharSequence
    Parameters:
    str - the CharSequence to check, may be null
    defaultStr - the default CharSequence to return if the input is whitespace, empty ("") or null, may be null
    
    Returns:
    the passed in CharSequence, or the default
    See Also:
    defaultString(String, String)
  - defaultIfEmpty
```
public static <T extends CharSequence> T defaultIfEmpty(T str,
                                        T defaultStr)
```
    Returns either the passed in CharSequence, or if the CharSequence is empty or null, the value of defaultStr.
```
 StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
 StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
 StringUtils.defaultIfEmpty(" ", "NULL")   = " "
 StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
 StringUtils.defaultIfEmpty("", null)      = null
 
```
    Type Parameters:
    T - the specific kind of CharSequence
    Parameters:
    str - the CharSequence to check, may be null
    defaultStr - the default CharSequence to return if the input is empty ("") or null , may be null
    
    Returns:
    the passed in CharSequence, or the default
    See Also:
    defaultString(String, String)
  - reverse
```
public static String reverse(String str)
```
    Reverses a String as per StringBuilder.reverse().
    
    A null String returns null.
```
 StringUtils.reverse(null)  = null
 StringUtils.reverse("")    = ""
 StringUtils.reverse("bat") = "tab"
 
```
    Parameters:
    str - the String to reverse, may be null
    
    Returns:
    the reversed String, null if null String input
  - reverseDelimited
```
public static String reverseDelimited(String str,
                      char separatorChar)
```
    Reverses a String that is delimited by a specific character.
    
    The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is '.').
```
 StringUtils.reverseDelimited(null, *)      = null
 StringUtils.reverseDelimited("", *)        = ""
 StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
 StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
 
```
    Parameters:
    str - the String to reverse, may be null
    separatorChar - the separator character to use
    
    Returns:
    the reversed String, null if null String input
    Since:
    
    2.0
  - abbreviate
```
public static String abbreviate(String str,
                int maxWidth)
```
    Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."
    
    Specifically:
    - If str is less than maxWidth characters long, return it.
    - Else abbreviate it to (substring(str, 0, max-3) + "...").
    - If maxWidth is less than 4, throw an IllegalArgumentException.
    - In no case will it return a String of length greater than maxWidth.
```
 StringUtils.abbreviate(null, *)      = null
 StringUtils.abbreviate("", 4)        = ""
 StringUtils.abbreviate("abcdefg", 6) = "abc..."
 StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 4) = "a..."
 StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
 
```
    Parameters:
    str - the String to check, may be null
    maxWidth - maximum length of result String, must be at least 4
    
    Returns:
    abbreviated String, null if null String input
    
    Throws:
    
    IllegalArgumentException - if the width is too small
    Since:
    
    2.0
  - abbreviate
```
public static String abbreviate(String str,
                int offset,
                int maxWidth)
```
    Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."
    
    Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.
    In no case will it return a String of length greater than maxWidth.
```
 StringUtils.abbreviate(null, *, *)                = null
 StringUtils.abbreviate("", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
 StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException
 
```
    Parameters:
    str - the String to check, may be null
    offset - left edge of source String
    maxWidth - maximum length of result String, must be at least 4
    
    Returns:
    abbreviated String, null if null String input
    
    Throws:
    
    IllegalArgumentException - if the width is too small
    Since:
    
    2.0
  - abbreviateMiddle
```
public static String abbreviateMiddle(String str,
                      String middle,
                      int length)
```
    Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.
    
    This abbreviation only occurs if the following criteria is met:
    - Neither the String for abbreviation nor the replacement String are null or empty
    - The length to truncate to is less than the length of the supplied String
    - The length to truncate to is greater than 0
    - The abbreviated String will have enough room for the length supplied replacement String and the first and last characters of the supplied String for abbreviation
    Otherwise, the returned String will be the same as the supplied String for abbreviation.
```
 StringUtils.abbreviateMiddle(null, null, 0)      = null
 StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
 StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"
 
```
    Parameters:
    str - the String to abbreviate, may be null
    middle - the String to replace the middle characters with, may be null
    length - the length to abbreviate str to.
    
    Returns:
    the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.
    Since:
    
    2.5
  - difference
```
public static String difference(String str1,
                String str2)
```
    Compares two Strings, and returns the portion where they differ. More precisely, return the remainder of the second String, starting from where it's different from the first. This means that the difference between "abc" and "ab" is the empty String and not "c".
    
    For example, difference("i am a machine", "i am a robot") -> "robot".
```
 StringUtils.difference(null, null) = null
 StringUtils.difference("", "") = ""
 StringUtils.difference("", "abc") = "abc"
 StringUtils.difference("abc", "") = ""
 StringUtils.difference("abc", "abc") = ""
 StringUtils.difference("abc", "ab") = ""
 StringUtils.difference("ab", "abxyz") = "xyz"
 StringUtils.difference("abcde", "abxyz") = "xyz"
 StringUtils.difference("abcde", "xyz") = "xyz"
 
```
    Parameters:
    str1 - the first String, may be null
    str2 - the second String, may be null
    
    Returns:
    the portion of str2 where it differs from str1; returns the empty String if they are equal
    Since:
    
    2.0
    
    See Also:
    indexOfDifference(CharSequence,CharSequence)
  - indexOfDifference
```
public static int indexOfDifference(CharSequence cs1,
                    CharSequence cs2)
```
    Compares two CharSequences, and returns the index at which the CharSequences begin to differ.
    
    For example, indexOfDifference("i am a machine", "i am a robot") -> 7
```
 StringUtils.indexOfDifference(null, null) = -1
 StringUtils.indexOfDifference("", "") = -1
 StringUtils.indexOfDifference("", "abc") = 0
 StringUtils.indexOfDifference("abc", "") = 0
 StringUtils.indexOfDifference("abc", "abc") = -1
 StringUtils.indexOfDifference("ab", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "xyz") = 0
 
```
    Parameters:
    cs1 - the first CharSequence, may be null
    cs2 - the second CharSequence, may be null
    
    Returns:
    the index where cs1 and cs2 begin to differ; -1 if they are equal
    Since:
    
    2.0, 3.0 Changed signature from indexOfDifference(String, String) to indexOfDifference(CharSequence, CharSequence)
  - indexOfDifference
```
public static int indexOfDifference(CharSequence... css)
```
    Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.
    
    For example, indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7
```
 StringUtils.indexOfDifference(null) = -1
 StringUtils.indexOfDifference(new String[] {}) = -1
 StringUtils.indexOfDifference(new String[] {"abc"}) = -1
 StringUtils.indexOfDifference(new String[] {null, null}) = -1
 StringUtils.indexOfDifference(new String[] {"", ""}) = -1
 StringUtils.indexOfDifference(new String[] {"", null}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
 StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
 StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
 StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
 StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
 StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7
 
```
    Parameters:
    css - array of CharSequences, entries may be null
    
    Returns:
    the index where the strings begin to differ; -1 if they are all equal
    Since:
    
    2.4, 3.0 Changed signature from indexOfDifference(String...) to indexOfDifference(CharSequence...)
  - getCommonPrefix
```
public static String getCommonPrefix(String... strs)
```
    Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.
    
    For example, getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "
```
 StringUtils.getCommonPrefix(null) = ""
 StringUtils.getCommonPrefix(new String[] {}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"", null}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
 StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
 StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
 StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "
 
```
    Parameters:
    strs - array of String objects, entries may be null
    
    Returns:
    the initial sequence of characters that are common to all Strings in the array; empty String if the array is null, the elements are all null or if there is no common prefix.
    Since:
    
    2.4
  - getLevenshteinDistance
```
public static int getLevenshteinDistance(CharSequence s,
                         CharSequence t)
```
    Find the Levenshtein distance between two Strings.
    
    This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).
    
    The previous implementation of the Levenshtein distance algorithm was from http://www.merriampark.com/ld.htm
    
    Chas Emerick has written an implementation in Java, which avoids an OutOfMemoryError which can occur when my Java implementation is used with very large strings.
    This implementation of the Levenshtein distance algorithm is from http://www.merriampark.com/ldjava.htm
```
 StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","")               = 0
 StringUtils.getLevenshteinDistance("","a")              = 1
 StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
 StringUtils.getLevenshteinDistance("frog", "fog")       = 1
 StringUtils.getLevenshteinDistance("fly", "ant")        = 3
 StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
 StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
 StringUtils.getLevenshteinDistance("hello", "hallo")    = 1
 
```
    Parameters:
    s - the first String, must not be null
    t - the second String, must not be null
    
    Returns:
    result distance
    
    Throws:
    
    IllegalArgumentException - if either String input null
    Since:
    
    3.0 Changed signature from getLevenshteinDistance(String, String) to getLevenshteinDistance(CharSequence, CharSequence)
  - getLevenshteinDistance
```
public static int getLevenshteinDistance(CharSequence s,
                         CharSequence t,
                         int threshold)
```
    Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.
    
    This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).
    
    This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield and Chas Emerick's implementation of the Levenshtein distance algorithm from http://www.merriampark.com/ld.htm
```
 StringUtils.getLevenshteinDistance(null, *, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, *, -1)               = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","", 0)               = 0
 StringUtils.getLevenshteinDistance("aaapppp", "", 8)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 7)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 6))      = -1
 StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7
 StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1
 StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1
 
```
    Parameters:
    s - the first String, must not be null
    t - the second String, must not be null
    threshold - the target threshold, must not be negative
    
    Returns:
    result distance, or -1 if the distance would be greater than the threshold
    
    Throws:
    
    IllegalArgumentException - if either String input null or negative threshold
  - getJaroWinklerDistance
```
public static double getJaroWinklerDistance(CharSequence first,
                            CharSequence second)
```
    Find the Jaro Winkler Distance which indicates the similarity score between two Strings.
    
    The Jaro measure is the weighted sum of percentage of matched characters from each file and transposed characters. Winkler increased this measure for matching initial characters.
    
    This implementation is based on the Jaro Winkler similarity algorithm from http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance.
```
 StringUtils.getJaroWinklerDistance(null, null)          = IllegalArgumentException
 StringUtils.getJaroWinklerDistance("","")               = 0.0
 StringUtils.getJaroWinklerDistance("","a")              = 0.0
 StringUtils.getJaroWinklerDistance("aaapppp", "")       = 0.0
 StringUtils.getJaroWinklerDistance("frog", "fog")       = 0.93
 StringUtils.getJaroWinklerDistance("fly", "ant")        = 0.0
 StringUtils.getJaroWinklerDistance("elephant", "hippo") = 0.44
 StringUtils.getJaroWinklerDistance("hippo", "elephant") = 0.44
 StringUtils.getJaroWinklerDistance("hippo", "zzzzzzzz") = 0.0
 StringUtils.getJaroWinklerDistance("hello", "hallo")    = 0.88
 StringUtils.getJaroWinklerDistance("ABC Corporation", "ABC Corp") = 0.91
 StringUtils.getJaroWinklerDistance("D N H Enterprises Inc", "D & H Enterprises, Inc.") = 0.93
 StringUtils.getJaroWinklerDistance("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.94
 StringUtils.getJaroWinklerDistance("PENNSYLVANIA", "PENNCISYLVNIA")    = 0.9
 
```
    Parameters:
    first - the first String, must not be null
    second - the second String, must not be null
    
    Returns:
    result distance
    
    Throws:
    
    IllegalArgumentException - if either String input null
    Since:
    
    3.3
  - startsWith
```
public static boolean startsWith(CharSequence str,
                 CharSequence prefix)
```
    Check if a CharSequence starts with a specified prefix.
    
    nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.startsWith(null, null)      = true
 StringUtils.startsWith(null, "abc")     = false
 StringUtils.startsWith("abcdef", null)  = false
 StringUtils.startsWith("abcdef", "abc") = true
 StringUtils.startsWith("ABCDEF", "abc") = false
 
```
    Parameters:
    str - the CharSequence to check, may be null
    prefix - the prefix to find, may be null
    
    Returns:
    true if the CharSequence starts with the prefix, case sensitive, or both null
    Since:
    
    2.4, 3.0 Changed signature from startsWith(String, String) to startsWith(CharSequence, CharSequence)
    
    See Also:
    String.startsWith(String)
  - startsWithIgnoreCase
```
public static boolean startsWithIgnoreCase(CharSequence str,
                           CharSequence prefix)
```
    Case insensitive check if a CharSequence starts with a specified prefix.
    
    nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.
```
 StringUtils.startsWithIgnoreCase(null, null)      = true
 StringUtils.startsWithIgnoreCase(null, "abc")     = false
 StringUtils.startsWithIgnoreCase("abcdef", null)  = false
 StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
 StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true
 
```
    Parameters:
    str - the CharSequence to check, may be null
    prefix - the prefix to find, may be null
    
    Returns:
    true if the CharSequence starts with the prefix, case insensitive, or both null
    Since:
    
    2.4, 3.0 Changed signature from startsWithIgnoreCase(String, String) to startsWithIgnoreCase(CharSequence, CharSequence)
    
    See Also:
    String.startsWith(String)
  - startsWithAny
```
public static boolean startsWithAny(CharSequence string,
                    CharSequence... searchStrings)
```
    Check if a CharSequence starts with any of an array of specified strings.
```
 StringUtils.startsWithAny(null, null)      = false
 StringUtils.startsWithAny(null, new String[] {"abc"})  = false
 StringUtils.startsWithAny("abcxyz", null)     = false
 StringUtils.startsWithAny("abcxyz", new String[] {""}) = false
 StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
 StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
 
```
    Parameters:
    string - the CharSequence to check, may be null
    searchStrings - the CharSequences to find, may be null or empty
    
    Returns:
    true if the CharSequence starts with any of the the prefixes, case insensitive, or both null
    Since:
    
    2.5, 3.0 Changed signature from startsWithAny(String, String[]) to startsWithAny(CharSequence, CharSequence...)
  - endsWith
```
public static boolean endsWith(CharSequence str,
               CharSequence suffix)
```
    Check if a CharSequence ends with a specified suffix.
    
    nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.endsWith(null, null)      = true
 StringUtils.endsWith(null, "def")     = false
 StringUtils.endsWith("abcdef", null)  = false
 StringUtils.endsWith("abcdef", "def") = true
 StringUtils.endsWith("ABCDEF", "def") = false
 StringUtils.endsWith("ABCDEF", "cde") = false
 
```
    Parameters:
    str - the CharSequence to check, may be null
    suffix - the suffix to find, may be null
    
    Returns:
    true if the CharSequence ends with the suffix, case sensitive, or both null
    Since:
    
    2.4, 3.0 Changed signature from endsWith(String, String) to endsWith(CharSequence, CharSequence)
    
    See Also:
    String.endsWith(String)
  - endsWithIgnoreCase
```
public static boolean endsWithIgnoreCase(CharSequence str,
                         CharSequence suffix)
```
    Case insensitive check if a CharSequence ends with a specified suffix.
    
    nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.
```
 StringUtils.endsWithIgnoreCase(null, null)      = true
 StringUtils.endsWithIgnoreCase(null, "def")     = false
 StringUtils.endsWithIgnoreCase("abcdef", null)  = false
 StringUtils.endsWithIgnoreCase("abcdef", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false
 
```
    Parameters:
    str - the CharSequence to check, may be null
    suffix - the suffix to find, may be null
    
    Returns:
    true if the CharSequence ends with the suffix, case insensitive, or both null
    Since:
    
    2.4, 3.0 Changed signature from endsWithIgnoreCase(String, String) to endsWithIgnoreCase(CharSequence, CharSequence)
    
    See Also:
    String.endsWith(String)
  - normalizeSpace
```
public static String normalizeSpace(String str)
```
    Similar to http://www.w3.org/TR/xpath /#function-normalize -space
    
    The function returns the argument string with whitespace normalized by using trim(String) to remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.
    In XML Whitespace characters are the same as those allowed by the S production, which is S ::= (#x20 | #x9 | #xD | #xA)+
    Java's regexp pattern \s defines whitespace as [ \t\n\x0B\f\r]
    For reference:
    - \x0B = vertical tab
    - \f = #xC = form feed
    - #x20 = space
    - #x9 = \t
    - #xA = \n
    - #xD = \r
    The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also normalize. Additionally trim(String) removes control characters (char <= 32) from both ends of this String.
    Parameters:
    str - the source String to normalize whitespaces from, may be null
    
    Returns:
    the modified string with whitespace normalized, null if null String input
    Since:
    
    3.0
    
    See Also:
    Pattern, trim(String), http://www.w3.org/TR/xpath/#function-normalize-space
  - endsWithAny
```
public static boolean endsWithAny(CharSequence string,
                  CharSequence... searchStrings)
```
    Check if a CharSequence ends with any of an array of specified strings.
```
 StringUtils.endsWithAny(null, null)      = false
 StringUtils.endsWithAny(null, new String[] {"abc"})  = false
 StringUtils.endsWithAny("abcxyz", null)     = false
 StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true
 
```
    Parameters:
    string - the CharSequence to check, may be null
    searchStrings - the CharSequences to find, may be null or empty
    
    Returns:
    true if the CharSequence ends with any of the the prefixes, case insensitive, or both null
    Since:
    
    3.0
  - appendIfMissing
```
public static String appendIfMissing(String str,
                     CharSequence suffix,
                     CharSequence... suffixes)
```
    Appends the suffix to the end of the string if the string does not already end with any the suffixes.
```
 StringUtils.appendIfMissing(null, null) = null
 StringUtils.appendIfMissing("abc", null) = "abc"
 StringUtils.appendIfMissing("", "xyz") = "xyz"
 StringUtils.appendIfMissing("abc", "xyz") = "abcxyz"
 StringUtils.appendIfMissing("abcxyz", "xyz") = "abcxyz"
 StringUtils.appendIfMissing("abcXYZ", "xyz") = "abcXYZxyz"
 
```
    With additional suffixes,
```
 StringUtils.appendIfMissing(null, null, null) = null
 StringUtils.appendIfMissing("abc", null, null) = "abc"
 StringUtils.appendIfMissing("", "xyz", null) = "xyz"
 StringUtils.appendIfMissing("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
 StringUtils.appendIfMissing("abc", "xyz", "") = "abc"
 StringUtils.appendIfMissing("abc", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissing("abcxyz", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissing("abcmno", "xyz", "mno") = "abcmno"
 StringUtils.appendIfMissing("abcXYZ", "xyz", "mno") = "abcXYZxyz"
 StringUtils.appendIfMissing("abcMNO", "xyz", "mno") = "abcMNOxyz"
 
```
    Parameters:
    str - The string.
    suffix - The suffix to append to the end of the string.
    suffixes - Additional suffixes that are valid terminators.
    
    Returns:
    A new String if suffix was appened, the same string otherwise.
    Since:
    
    3.2
  - appendIfMissingIgnoreCase
```
public static String appendIfMissingIgnoreCase(String str,
                               CharSequence suffix,
                               CharSequence... suffixes)
```
    Appends the suffix to the end of the string if the string does not already end, case insensitive, with any of the suffixes.
```
 StringUtils.appendIfMissingIgnoreCase(null, null) = null
 StringUtils.appendIfMissingIgnoreCase("abc", null) = "abc"
 StringUtils.appendIfMissingIgnoreCase("", "xyz") = "xyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz") = "abcXYZ"
 
```
    With additional suffixes,
```
 StringUtils.appendIfMissingIgnoreCase(null, null, null) = null
 StringUtils.appendIfMissingIgnoreCase("abc", null, null) = "abc"
 StringUtils.appendIfMissingIgnoreCase("", "xyz", null) = "xyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "") = "abc"
 StringUtils.appendIfMissingIgnoreCase("abc", "xyz", "mno") = "axyz"
 StringUtils.appendIfMissingIgnoreCase("abcxyz", "xyz", "mno") = "abcxyz"
 StringUtils.appendIfMissingIgnoreCase("abcmno", "xyz", "mno") = "abcmno"
 StringUtils.appendIfMissingIgnoreCase("abcXYZ", "xyz", "mno") = "abcXYZ"
 StringUtils.appendIfMissingIgnoreCase("abcMNO", "xyz", "mno") = "abcMNO"
 
```
    Parameters:
    str - The string.
    suffix - The suffix to append to the end of the string.
    suffixes - Additional suffixes that are valid terminators.
    
    Returns:
    A new String if suffix was appened, the same string otherwise.
    Since:
    
    3.2
  - prependIfMissing
```
public static String prependIfMissing(String str,
                      CharSequence prefix,
                      CharSequence... prefixes)
```
    Prepends the prefix to the start of the string if the string does not already start with any of the prefixes.
```
 StringUtils.prependIfMissing(null, null) = null
 StringUtils.prependIfMissing("abc", null) = "abc"
 StringUtils.prependIfMissing("", "xyz") = "xyz"
 StringUtils.prependIfMissing("abc", "xyz") = "xyzabc"
 StringUtils.prependIfMissing("xyzabc", "xyz") = "xyzabc"
 StringUtils.prependIfMissing("XYZabc", "xyz") = "xyzXYZabc"
 
```
    With additional prefixes,
```
 StringUtils.prependIfMissing(null, null, null) = null
 StringUtils.prependIfMissing("abc", null, null) = "abc"
 StringUtils.prependIfMissing("", "xyz", null) = "xyz"
 StringUtils.prependIfMissing("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
 StringUtils.prependIfMissing("abc", "xyz", "") = "abc"
 StringUtils.prependIfMissing("abc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissing("xyzabc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissing("mnoabc", "xyz", "mno") = "mnoabc"
 StringUtils.prependIfMissing("XYZabc", "xyz", "mno") = "xyzXYZabc"
 StringUtils.prependIfMissing("MNOabc", "xyz", "mno") = "xyzMNOabc"
 
```
    Parameters:
    str - The string.
    prefix - The prefix to prepend to the start of the string.
    prefixes - Additional prefixes that are valid.
    
    Returns:
    A new String if prefix was prepended, the same string otherwise.
    Since:
    
    3.2
  - prependIfMissingIgnoreCase
```
public static String prependIfMissingIgnoreCase(String str,
                                CharSequence prefix,
                                CharSequence... prefixes)
```
    Prepends the prefix to the start of the string if the string does not already start, case insensitive, with any of the prefixes.
```
 StringUtils.prependIfMissingIgnoreCase(null, null) = null
 StringUtils.prependIfMissingIgnoreCase("abc", null) = "abc"
 StringUtils.prependIfMissingIgnoreCase("", "xyz") = "xyz"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz") = "XYZabc"
 
```
    With additional prefixes,
```
 StringUtils.prependIfMissingIgnoreCase(null, null, null) = null
 StringUtils.prependIfMissingIgnoreCase("abc", null, null) = "abc"
 StringUtils.prependIfMissingIgnoreCase("", "xyz", null) = "xyz"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", new CharSequence[]{null}) = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "") = "abc"
 StringUtils.prependIfMissingIgnoreCase("abc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("xyzabc", "xyz", "mno") = "xyzabc"
 StringUtils.prependIfMissingIgnoreCase("mnoabc", "xyz", "mno") = "mnoabc"
 StringUtils.prependIfMissingIgnoreCase("XYZabc", "xyz", "mno") = "XYZabc"
 StringUtils.prependIfMissingIgnoreCase("MNOabc", "xyz", "mno") = "MNOabc"
 
```
    Parameters:
    str - The string.
    prefix - The prefix to prepend to the start of the string.
    prefixes - Additional prefixes that are valid (optional).
    
    Returns:
    A new String if prefix was prepended, the same string otherwise.
    Since:
    
    3.2
  - wrap
```
public static String wrap(String str,
          char wrapWith)
```
    Wraps a string with a char.
```
 StringUtils.wrap(null, *)        = null
 StringUtils.wrap("", *)          = ""
 StringUtils.wrap("ab", '\0')     = "ab"
 StringUtils.wrap("ab", 'x')      = "xabx"
 StringUtils.wrap("ab", '\'')     = "'ab'"
 StringUtils.wrap("\"ab\"", '\"') = "\"\"ab\"\""
 
```
    Parameters:
    str - the string to be wrapped, may be null
    wrapWith - the char that will wrap str
    
    Returns:
    the wrapped string, or null if str==null
    Since:
    
    3.4
  - wrap
```
public static String wrap(String str,
          String wrapWith)
```
    Wraps a String with another String.
    
    A null input String returns null.
```
 StringUtils.wrap(null, *)         = null
 StringUtils.wrap("", *)           = ""
 StringUtils.wrap("ab", null)      = "ab"
 StringUtils.wrap("ab", "x")       = "xabx"
 StringUtils.wrap("ab", "\"")      = "\"ab\""
 StringUtils.wrap("\"ab\"", "\"")  = "\"\"ab\"\""
 StringUtils.wrap("ab", "'")       = "'ab'"
 StringUtils.wrap("'abcd'", "'")   = "''abcd''"
 StringUtils.wrap("\"abcd\"", "'") = "'\"abcd\"'"
 StringUtils.wrap("'abcd'", "\"")  = "\"'abcd'\""
 
```
    Parameters:
    str - the String to be wrapper, may be null
    wrapWith - the String that will wrap str
    
    Returns:
    wrapped String, null if null String input
    Since:
    
    3.4

Class StringUtils

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SPACE

EMPTY

LF

CR

INDEX_NOT_FOUND

Constructor Detail

StringUtils

Method Detail

isEmpty

isNotEmpty

isAnyEmpty

isNoneEmpty

isBlank

isNotBlank

isAnyBlank

isNoneBlank

trim

trimToNull

trimToEmpty

strip

stripToNull

stripToEmpty

strip

stripStart

stripEnd

stripAll

stripAll

equals

equalsIgnoreCase

indexOf

indexOf

indexOf

indexOf

ordinalIndexOf

indexOfIgnoreCase

indexOfIgnoreCase

lastIndexOf

lastIndexOf

lastIndexOf

lastOrdinalIndexOf

lastIndexOf

lastIndexOfIgnoreCase

lastIndexOfIgnoreCase

contains

contains

containsIgnoreCase

containsWhitespace

indexOfAny

indexOfAny

containsAny

containsAny

indexOfAnyBut

indexOfAnyBut

containsOnly

containsOnly

containsNone

containsNone

indexOfAny

lastIndexOfAny

substring

substring

left

right

mid

substringBefore

substringAfter

substringBeforeLast

substringAfterLast

substringBetween

substringBetween

substringsBetween

split

split

split